I guess my wishlist would be the following:
1) Geoff: He is entertaining as all hell, good at rules lawyering as I've seen an individual be, and our single best shot at possibly getting a Warhammer 40K themed Rollplay show of any size or scope back on the Rollplay banner should Steven still be gun shy about it. Plus with Fantasy Flight Games no longer having license to the RPG books, proving to Games Workshop that hey, the RPG scene isn't something they should totally shun just because they are making tons of money off of models would be nice.
2) Matt Mercer: Yes he's the dream GM, adept at a great many systems but I fear his schedule wouldn't make it truly feasible. Still though, it's a wish list so he's got to be on it. I do prefer him as a player on the one shots he's done with Rollplay though and thinks he enjoys it more than always constantly being behind a DM screen no matter where he goes.
3) Vincent Baker: You already have Adam and John who have their own systems inspired by Apocalypse World, might as well bring him on board and do a proper Apocalypse World session (no knocks to Adam for his own Roll20 Apocalypse World campaign mind you).
4) Steven: I really would like him to come back to the Rollplay banner in some way shape or form even if it's just for a yearly Maids RPG one-shot as was tradition.
5) Jesse Cox: Just like Geoff, Jesse is immensely entertaining and creative which could be well suited for trying his hand at a one shot. Plus the sibling like rivalry he's got going with Dodger would be an amusing way for him to try his hand at it, since Dodger actually went ahead and DM'ed a one shot while he has yet to man up to try and take the reigns himself. If we can egg him on, his delightful ego won't let it stand for long and he'll probably be chomping at the bit to give it a try, especially if even Crendor of all people is considered. If nothing else and if Steven really isn't coming back to Rollplay, then Jesse at the very least should pick up the mantle for DM'ing the Maids RPG one-shot to start the tradition anew.