I don't know if we're ever going back to that same level of wacky adventures.
But this is a character-driven show, even if it's growing an overarching plot fast. The writers are good, they know what makes the show work, and I don't think the "real" plot will overshadow or get in the way of the important stuff, which is Star and Marco.
I think the situation going into S3 is the looming threat of Toffee and Star having to deal with that. I assume the biggest impact this will have is Moon taking over Star's magic training because she's going to have to be able to handle herself and the Wand. In that situation, Star isn't going to be doing much in the way of adventuring or having fun in general. If that's the situation, it's going to have to be resolved sooner than later because this isn't that kind of show and the audience needs to get back into some kind of comfort zone.
I think there's a real chance Season 3 opens with a bang, at least on the Mewni side, and either Toffee suffers his first major setback (enough that everyone can relax for a while and we can return to some normalcy) or shit hits the fan at full blast and Castle Butterfly is actually overrun right from the start.
If Moon can keep Star in the castle on the defensive, the story isn't going to move anywhere and nothing interesting is going to happen.
If they actually lose the castle, and who knows what else, then we actually have some twisted return to a recognizable status quo, with Star on the run across Mewni as the new "adventures."