I think the ideal situation is for this rumor to lead two "main series". A modernized open world one on higher end consoles, and a traditional Monster Hunter series that sticks to mobile platforms. Think something like how 2D Mario and 3D Mario co-exist.
However, assuming the rumor is true, I'm not convinced all of the worries are just fanboy wars. The rumor straight up mentions internal strike at Capcom over this. Even ignoring that aspect, Capcom hasn't had a great track record with their "simplifications" in recent time, most notably look at how Dead Rising 4 tanked.
Things may be different of course, since I believe Dead Rising 4 was made by one of Capcom's Western studios, so maybe the Japanese side will have a better shot at their simplification. Still though, with the way the rumor is framed, it doesn't seem like the PS4 Monster Hunter has had a smooth ride. Hopefully, Monster Hunter 5 will end up succeeding, or else it, at best, will probably lead to Capcom losing a pretty large chunk of cash in a vulnerable time, even if they can maybe soften the blow with a traditional Monster Hunter portable.