That's what I was thinking, because as I spent some more time with Fifa 17 last week and this weekend I noticed, the core part of the game, the menus, the front end of the career/franchise mode etc was exactly as it's always been as far as I could tell. Nothing on that end changed. It's not like features of it got left out in the engine switch, they all appear intact. I really didn't notice much difference in the gameplay on the field either, aside from much improved visuals and lighting.
I just don't think this switch will be a major inconvenience at all, but I'm sure every little molehill will get turned into a mountain and blamed on frostbite.