Actually, when it comes to systems, they kinda going in opposite direction right at the moment, from what I read. The started cleaning useless systems, like this whole threat level. And I think it is wise: to combat feature creep. And as I wrote, the trick is not to have some useless system just to have it, but the system must be meaningful to your goals. So their stated goal is now adding content and they are treating game as feature complete. And, although no news was posted about it recently, they probably still working on SU:Rebuilt?
My propositions are specifically thought as low-effort in development and asset creation (kinda writing heavy). I might have wrong assumptions about where real bottlenecks are, in my mind hardest and most time consuming is creation of art assets. So I mostly thing about reusing existing ones in new ways. Just use existing location and existing characters, maybe adding selected few that are conspicuously missing. Like maybe Superman and or Clark Kent could be reasonable cameo in Lex Luthor game?