It'll be different, but ultimately it's likely to be similar systems to what we have now, so if you're getting tired of the core gameplay loop of PSO2 I doubt NGS will be that different. Some new options for getting items might be neat, but also I don't think a game should necessarily branch out of what it's good at just to stay fresh, because that's a good way for a game to start feeling like a mess too.
I think it's also worth noting that even with NGS's new systems, the content is likely to be immensely slower (and less of it to start with) than what we've become accustomed to in Global. I wouldn't be surprised if a lot of people were enamored with NGS on its release, but after they hit max level and the honeymoon phase ends, they just end up thinking "what... that's it?"
If you think you might be getting tired of PSO2, just stop playing it and come back when you feel like it. There's a good quote from the director of FFXIV about this when someone asks him "how do I make myself keep interested in your game" that could apply here too (just pretend they're talking about PSO2):
"Hey YoshiP, I love FFXIV, but it's hard to keep playing your game (because of the lack of content) and now I'm taking a break here. Sorry for asking this but is there a way or a reason to keep playing? or anything that can you teach me how to keep my motivation for playing your game?" - A player asking Yoshida during Gamescom
Yoshida "It's alright not to play it everyday. Since it's just a game, you can stop forcing yourself if it's hard on you to keep that up. Rather, it'll just pile up unnecessary stress if you limit yourself into playing just that one game since there are so many other games out there. So, do come back and play it to your heart's content when the major patch kicks in, then stop it to play other games before you got burnt out, and then come back for another major patch. This will actually make me happier, and in the end, I think this is the best solution I can answer for keeping your motivation up for the game."