two of my dream games already came to life with a new Jet Set Radio and a new Sorcery Saga having been announced (three if you count Sonic x Shadow Generations as a potential sequel to Shadow the Hedgehog, but i'm, uh...cautiously optimistic about that one, to put it very lightly)
but that aside, one game idea i really want is just an rpg that reuses The World Ends with You's original battle system, where you essentially control two party members simultaneously in real time (potentially with different input methods for either character, but i'm not sure how possible that is with most modern hardware). i don't even think it'd be that difficult to pull off on something that isn't the DS, i thought the 2 player mode in the switch version would've been ideal with a bit of refinement, so it irritates me that nobody's tried it. this also applies to Chain of Memories on the GBA.
there's this one imageboard i use where someone proposed the idea of an open world game where you play as a magical girl, having the option of going to school or doing normal girl things around town and/or finding enemies causing havoc on the map and transforming to fight them, and i thought that sounded fun.