Would they take the entire market share? Would they make Micro Four Thirds the most popular format out there? There have been tons of new rumors on many websites that Fuji is planning on releasing a Micro Four Thirds camera in September. Thom Hogan (a prominent figure) has mentioned that a prototype has even been tested, but the decision of release has not been made yet (but most likely will). So what would a Fuji camera mean for Micro Four Thirds?

id be dancing in the streets , i tell ya!

More cameras, more lenses, more accecoires....
Resulting in more competition and last but not least lower prices !

i like  the positive vibe this intriguing rumor is providing

it look like it might actually be true

So what would a Fuji camera mean for Micro Four Thirds?

It would increase the availability of cameras/lenses and strengthen the presence of m4/3 in general. No matter consumer, professional, or premium cameras/lenses they would make, the presence of yet another active player will broaden recognition for the standard and will eventually be beneficiary for all of the companies inside and for buyers themselves.
I can't imagine another way for Fujy to sell cameras compatible with lenses from Olympus and Panasonic and vice-versa.

m4/3 would be a great standard if companies did not have to pay to Oly for using it.

A third camera manufacturer most definitely would be more than welcome as it would increase the significance of µFT. 
But I don't think that it would mean more than exactly that.
If I'm not mistaken Fuji never have produced own lenses for their DSLRs, so why should anyone believe they would do so for an µFT camera.

And sensorwise they have been very good some years ago but since then, they have gone somewhat backwards, haven't they. Ans despite being a layman I have my doubts if a Super CCD would meet the needs a camara has to meet today regarding areas such high ISOs or AF speed. And don't forget: they are using a Sony sensor for their X100. 
So, Id welcome the move but wouldn't expect too much. 

Fuji SLRs used Nikon mount I believe, so they wouldn't have any need to produce any lenses there.

That's what I wanted to say. They hadn't to. So why should they do in µFT?

I think if Fuji joined m4/3, it would be good for m4/3, but not necessarily good for Fuji or the photographic equipment market as a whole.

The more players in m4/3, the harder it would be for any other system to compete, but for each player inside m4/3, they would still have fight amongst themselves for share.

I don't know. The more players im µFT, the more they would pressurise each other to make progress - in lens quality, AF/C-AF speed, sensosrs and so on. And in addition, there would be more parties such as Sigma interested in producing native µFT lenses as the market potential for them would be growing.

The only way out is if any player would join and be compatible, but be different enough. For example, my biggest hate of m4/3 lenses is manual focus by wire. I don't see Olympus or Panasonic changing that except on highest models, but if Fuji joined and bought out a parallel line with decent lens handling, that would improve the situation significantly (or Sigma or anyone else could too.)

As I said: I don't see them prodicing their own lenses.

I think overall I would be more interested to see what independent system Fuji could come up with themselves than be limited to m4/3.

Do you think they've got the power to do so?
Why then didn't they come up with thieir own DSLR mount. So, i think that the chances for this are even smaller for Fuji µFT lenses.

We shouldnt forget that Fuji can produce their lenses as well, not even this is what their chief said but they actually produce lenses for Hasselblad systems, for example.

I simply fail to see why Fuj, having had great success with an APS-C sensor on the x-100, would now suddenly turn around and drop it in favor of a m43 sensor format. This is especially true if they want to make a run for the top. Why be a bit player alongside a Panasonic-dominated m43, if you feel you have a good chance of producing the new standard for mirror-less cameras?

Specifically replying to DonParrot's reply to my earlier post:

I don't know the history of how Fuji ended up doing bodies only with Nikon mount. I guess they made the decision they weren't interested in going against the existing players, but still wanted to do something. So throwing in a few bodies was a way they could play there. That's a world different from competing against long established major players.

Mirrorless system cameras are a totally different story. I still consider it at the entry level of market growth and while m4/3 might have some early adopter advantage, a determined drive from a new entrant now could still shake things up. It is still all to play for. I think the key for the players yet to show their cards is to come up with something different. I think m4/3 and NEX are capable mid range players. The Q, and possible future Nikon mirrorless aim a little lower. Canon is anyone's guess. Fuji I think have a chance. Rather than join the middle of the field as yet another "me too" player, could they continue on the X100 run and aim for a higher end system from the start? I think there is room for one player to go straight for premium end. They wont need a massive selection of lenses. By going high end, they can avoid the need for a mass of generic zooms and can concentrate on primes. Think Leica M series, but cheaper. It will be niche, but priced right, it could be a pretty big and profitable one.

I think Fuji have the expertise to do that. Whether they have the business bravery to attempt it, and the cash to get it going, is possibly another matter.

Specifically replying to DonParrot's reply to my earlier post:

I don't know the history of how Fuji ended up doing bodies only with Nikon mount. I guess they made the decision they weren't interested in going against the existing players, but still wanted to do something. So throwing in a few bodies was a way they could play there. That's a world different from competing against long established major players.

Mirrorless system cameras are a totally different story. I still consider it at the entry level of market growth and while m4/3 might have some early adopter advantage, a determined drive from a new entrant now could still shake things up. It is still all to play for. I think the key for the players yet to show their cards is to come up with something different. I think m4/3 and NEX are capable mid range players. The Q, and possible future Nikon mirrorless aim a little lower. Canon is anyone's guess. Fuji I think have a chance. Rather than join the middle of the field as yet another "me too" player, could they continue on the X100 run and aim for a higher end system from the start? I think there is room for one player to go straight for premium end. They wont need a massive selection of lenses. By going high end, they can avoid the need for a mass of generic zooms and can concentrate on primes. Think Leica M series, but cheaper. It will be niche, but priced right, it could be a pretty big and profitable one.

I think Fuji have the expertise to do that. Whether they have the business bravery to attempt it, and the cash to get it going, is possibly another matter.

You said it so more eloquently then I did in the 1st reply. I hope Fuji also goes straight to the premium body. There really isn't a big need to develop quality primes, but, there is always room for new offerings from another company that has a different idea on build and functional design. Maybe an optional manual focus collar with a DOF scale and f/stop ring maybe a Fuji lens feature they incorporate on their prime lenses, if they build any. and we all know now,  that Fuji has build many Hassalblad lenses in the past.

I am hoping they do enter the m4/3 with a premium body and possibly some great primes.... Time will tell.

I see no reason why they can't continue with an X100 line... In their Medium Format RFs, they had a few offerings, one with a wide angle, one with a Standard, and one with a short AF Zoom.  And few variations of each.