I don't really like the whole THIGHZA thing either, but one thing worth pointing out is that the Arland trilogy gradually ramped up the fanservice too until finally you got that hilariously thirsty hot springs scene in Meruru that was literally just naked people with strategically placed steam puffs. (They also had a "boys" version of that scene, so I guess it was at least somewhat equal opportunity.) The trilogy right after that reeled in the fanservice almost to the point of being non-existent.
So I don't think Ryza's marketing necessarily puts the franchise on an inevitable decline into life and hometown. Plus, as other people have mentioned before, the actual game doesn't have any fanservice besides the character designs. No skimpy hot springs scenes, no stupid boob size conversations (that I remember, anyway), no shopkeeper molestations. I definitely don't like the emphasis on THIGHZA but I'd still rather have the franchise be around than not, and if this gets us through to the next trilogy I'm happy to see where it goes.
Personally, I hope they change up the alchemy system at least somewhat for Ryza 2. It's probably my least favourite alchemy system since the Arland trilogy; I just found it so cumbersome to deal with, especially if you get a few phases into a recipe chain and realize late that you're missing some ingredients. Trying to remember every ingredient you used up to that point was annoying as hell. The change to combat to make items more important is nice, at least.