If FFVIIre actually makes it to PS4, and I'm still living in Japan, I will do my part and get one (since I also want persona 5 and a blu-ray player, hopefully more interesting games or old libraries will be available by then) but it will still be a few years until then, I think.
It's too early to have any idea how it's going to do. It should be big but I don't know if it will be "big enough"