Before E-M1 II + 12-100mm, I was considering LX100 to replace my C-7070. I prefer the "rangefinder" style: not only looks cooler, but also more discreet, so also more practical. But I eventually I decided I am not a street photographer anyways so discreet is not so important.
Maybe the reported dust issues of the LX100 did not inspire confidence either. After all, isn't avoiding dust on the sensor supposed to be one of the benefits of fixed lens camera? Dust in a fixed lens camera is even worse because you can't clean it. So, yeah... that was weird. So I shifted my attention to GX9 instead and eventually to Olympus.
I think if there is a new Pen F it can appeal a lot to street photographers, especially if they ever come out with a new version of 25mm with manual focus clutch. I don't think they don't need to make any more pro or prosumer-level fixed lens cameras for that. It would just be filling a niche, and it would overlap too much with their existing products.
I am not sure whether I would buy one or not - however I am not sure why the "full frame" part is important. While a guess a number of people would like to dip their toes into FF without going "all in", for me the important part of a fixed lens camera is a convenient size and weight. It should easily fit in a daily bag without requiring too much space or upping the weight of the whole pack buy a lot.
That's why, pricing completely aside, I ruled out the Q2: It's too large and heavy. About 50% more weight compared to the X100V and even with my Haoge squarehood the lens of the Fuji is still shorter than the Leica without a hood. The older Sony RX1R II on the other side is pretty comparable to the X100V, but I don't like the pop-up EVF design. Also it doesn't have a front dial and no weather sealing. However it impressively shows how compact and light a FF camera can actually be, in fact I was really surprised how small it is. Yet there never was a true successor to my knowledge, which kind of means this kind of camera didn't really do as well as Sony had hoped - unlike the Leica Q, Ricoh GR or Fuji X100 series, which all had a number of updated models.
Now if OMDS would release a Pen-F Mk II as a fixed lens camera with a ~35mm equiv. lens, fully weather sealed, featuring a similar footprint of the existing Pen-F with the 17mm 1.8 and a similar weight, however updating some of the internals and get the lens to f1.4 with better optical quality, I would be kind of interested - but the sensor size would be more or less unimportant for me. Would I replace my X100V with such a camera? I'm not sure, maybe, maybe not. As of now I am not sure if OMDS is willing to create a high-end fixed lens camera for a more or less limited market. I can totally see a place for their compact, water proof Tough cameras, as well as for additonal ILC, but a premium P&S camera?