There are reports floating around that Panasonic may be about to enter the full-frame fixed lens camera space with an official announcement coming this month.
Currently, Leica and their Q3 is the only other camera in the FF fixed lens camera space (there is also the monochrom Q2 which actually costs more). Sony has recently discontinued their RX1 RII which you can still find at retailers for around $3300 USD. With Panasonic's close relationship with Leica through the L-Mount Alliance, they could have a hit on their hands with their first iteration. The Panasonic fixed lens compacts from back in the day were quite popular and very good.
Fuji has obviously had a lot of success with the XV series for the APS-C equivalent camera type, as these cameras will likely be hard to find for the foreseeable future.
The Leica Q3 is still experiencing back orders, and that's for a $5995 camera that was launched a year ago this month. The Fuji XV100 VI comes in at $1599 and blew away demand expectations, and that's not just from Fuji, that's from various retailers. A lot of retailers actually stopped accepting preorders for the camera.
Speculation is that the new fixed lens camera will be equipped with the same 24.2mp sensor from the Lumix S5 II, which is very good and is the best performing autofocus camera in the current Panasonic lineup.
The price point would have to be fairly aggressive, with the Lumix S5 II priced at $1999 (MSRP before rebates), there could be some wiggle room to get this camera down to around $3000-$3500 to make it a profitable endeavour. The Leica Q3 obviously has the “Leica Tax”, and they would likely have higher manufacturing costs than Panasonic. The Q3 is equipped with a superb Summilux 28mm f/1.7 lens, something Panasonic doesn't need to to do. A lens that's 90% as good would cost a lot less than the Leica variant.
No word on focal length or aperture, but we'd guess on it being a 35mm lens, as that would again be a bit cheaper than a 28mm lens to manufacture and not compete directly with the Q3 in that regard. A lot of people prefer 35mm to 28mm anyway. Panasonic does make a very good 35mm f/1.8 that retails for just shy of $700 USD (MSRP before rebates). Panasonic could also release a screw-on accessory to bring the lens to 24mm or 28mm and add a bit of a revenue stream for the people that want the option.
One area Panasonic could easily beat the Leica Q3 is in video performance. The Q3 does shoot 8K, but it definitely wasn't engineered with videographers/hybrid shooters in mind.
There is obviously demand in the space, and Panasonic may be the ideal company to give consumers another option.
There is also no brand loyalty at this point for the niche. Lots of Canon shooters own the Fuji's and this Canon shooter has always had a Q around.
Source: Mirrorless Rumors
I won't be surprised if an upcoming Pansonic FF compact is based off the Q3 with a different sensor.