ElectonAsh's CPS-1 is just getting started, so that is definitely a long way off. He is reverse-engineering from actual hardware though, so it will be good if it is ever completed. He has audio working more or less already and is relatively far along considering how early it is. He also just started porting Jaguar
A cycle-accurate 68000 soft core was released
recently that will be making its way into lots of cores eventually, and it just got added to Genesis.
Neo Geo absolutely will happen, and Furrtek is actively working on that. He said that even though it may require more SDRAM (that is not confirmed though, it may be doable without), he will make it happen
. I organized a Patreon raid
a few weeks ago when he expressed interest in MiSTer and he got a ton of support and said that he's dedicated to making it happen now. So we may need a Neo Geo hardware add-on board, but I have no doubt that is in our future. How far into the future though is unknown. Remember that he's been decapping Neo Geo MVS/AES/CD hardware for a while now for preservation purposes, so when that core hits, it could be the most accurate core ever released from the sound of it.
A new scaler is the big project that Sorge and everyone is wrapped up in currently. Once completed, it should drastically reduce the HDMI latency, give tons of new options, add coefficient support to all cores, and is immensely easier/faster to compile (and it's open-souce). That will plug right into all of the current cores and is a direct replacement for the old scaler without much work. There are some preview builds of it in the NES core already.
Oof, I'm out of breath!