I think they should do sequels if they can do them right. So far they proved they couldn't. (see FFXIII)
With XV, a team containing the core members of FFVII, FFVIII, IX, KH series, and Type-0, I can see them successfully making a good sequel to FFXV if there is enough to build on.
I don't think that will mean we will never nothing BUT sequels until that team moves onto something else, because this is SE we're talking about. Right now they could have a team working on FFXVI.







