I´d like to see ExcessiveProfanity, I think I heard him mention that he has played some DnD in his younger days although that memory might be conjured by my own mind...
Maybe a oneshot with Zeke as DM kind of Dark Souls inspired story with players ExcessiveProfanity,Witwix,ManVSGame or have Zeke as 4th player, and a "professional" DM such as Adam, it would be a ragtag of players but I think it would be a really funny show.
Oneshot with a "survival (ARMA/DayZ) FPS" inspired ruleset with Timthetatman,Lirik,Shorty and Sacriel.
Will Wheaton, Felicia Day, Matthew Mercer as a DM (highly unlikely he´d spend hours DM'ing for Rollplay when he spends so much time on Critical Role already)..
All Rollplay historys DM's as players in a oneshot, (Adam Koebel,Steven,Neal and John.)
I'd also like to see Kaitlyn and Shannon in some more rollplay shows!