Just offering an opinion as a long time video shooter that's actually used a Fujinon lens on a beta-cam. I think it could be profitable if it didn't require extensive re-engineering the XT2's internals, kind of like the Sony VG10/20/30 is basically a rehoused Nex5.
Canon created a cinema line from nothing and it's been a huge hit, so it can be done. I don't think it'll ever happen either. Just fun to speculate.
I shoot with the A7rII and I haven't seen any degradation between IBIS on and off. It may happen with lens based systems, I don't know, but a lot of this discussion falls into the internet myth category, much like the FF look.
chris joy got a reaction from Larry Bolch in Why Fuji should release a video based camera
chris joy got a reaction from T-Man in IBIS degrades image quality