The thing I see with the F55 and FS7, is what could they possibly change/add in the next generation of cameras that would make me want to upgrade? Just because manufacturers of all products (cars, phones, etc.) like to come out with new versions does not diminish the value of last year's model at all. Even the F3 I sold two years ago would still be serving me well if I hadn't wanted 4K and HFR for my own projects. Clients don't need it.
So I already have 4K, S-LOG, RAW, XAVC, MEPG, HFR up to 240 fps, 4 channels of audio, 14 stops of dynamic range, PL lens mount, etc. So it is hard to imagine what anyone could add to the next generation of cameras that would make me want to upgrade. Maybe a 2/3" 4K camera based on the F800 might get my interest, but that's about all I can think of.
Buying a camera these days is a lot like the advice I've always given about buying a tripod or lights. Don't buy the bare minimum that will just satisfy your current needs, look down the road and see where you might be a couple of years from now. Future proof your purchase, and also be proactive and educate your clients about how your new capabilitied benefit THEM. Don't wait for people to ask for __________, anticipate changes in the industry and sell your client on _________ when you have it and your competition does not. I think the old cliche, "if you build it, they will come" applies more often that people who don't want to invest in new gear tend to admit. If I was still making my living doing corporate video, you can be sure every single one of my clients would be doing 4K today because I'd talk them into it. HD is the new SD!