Last year, I pointed out how many big publishers came crawlin' back to Steam after trying their own things: EA, Activision, Microsoft. This year, for the first time ever, two Blizzard games released on Steam: Overwatch and Diablo 4.
This genuinely doesn't get talked about enough. Steam is a private company and Gabe Newell seems to be the de facto "head" of the company, despite its famously "flat" management structure. There is no guarantee a new leader will have the same values or lead the same way. There is ripe opportunity for Steam to become a steaming pile of shit. I don't know about the exact ownership structure beyond Newell, but unless the employees are far more empowered through things like ownership stake in the company, new leadership could effectively destroy how things currently work at Valve to be replaced by any number of terrible business decisions.