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?
Many ifs for me. Would it still be mirrorless? Would it still be a rather small camera (absolutely not larger than my Olympus OMD EM1 M2)? AND would it have better low light/high ISO capabilities than my M43 Olympus? If yes to all this, we can go on to the other ifs.
If the price was good, the lens had the right length and other properties, for example 15 or 17mm with the possibility to f1.7, then yes. Otherwise not. It could be an interesting addition for gig photography in our local venue. For everything else I'm happy with M43.
But honestly, I think I'd rather work on my skills to create better low light gig photos (I think my main problem has been that I've underexposed them) with my EM1M2 instead of buying yet another camera.
I have a Fuji X100 which I received as a gift. I know it's not FF. It takes great photographs, looks cool and fits a (bellows) pocket. It's on my bench now because I never use it so a FF fixed-lens? Nice idea but no, thanks.