FF13 and FF12 both had "sphere grid like" systems (for lack of a better term.. I suppose "skill tree" kind of works as a term). They called them licences and crystariums but all much the same thing
FF12 had MMORPG-like combat. 13 was more hack and slash like. Definitely won't be turn based though!
If they're making it like the newer games, then... the newer games are a good reference point.