E3 without Sony is gonna be weird but I feel like all other conferences will be somewhat lowkey next year so their absence might not be drastic:
EA (The SPORTS/Fallen Order/Titanfall 3 Show)
Microsoft (I could see them going back to Mondays. I also think they are in a hell of a spot if they don't bring Halo to the show because I doubt any of their new studios have anything to show, except for maybe Playground and The Initiative. We can at least expect LOTS of 3rd party trailers and reveals.)
Bethesda (I'd be shocked if they have a show next year, unless they have Starfield ready to shown it will just be Doom, Wolfenstein games and ESO)
Devolver (Might as well finish the Trilogy)
Ubisoft (They might end up having the best show if they bring Splinter Cell and Watch Dogs 3 and maybe even another Rayman game)
PC Gaming (They're getting better, I like their low key PC games showings)
Square Enix (After this year, they better not have one unless they have FFVIIR, XVI and the Avengers game to show off)
Nintendo (Metroid and Pokemon are going to be the highlight for sure...hopefully)
I could see WB having their own conference, they have too many cards on hand (Rocksteady, MK, Harry Potter, Monolith, WB Montreal) and they haven't shown any of them.