Update May 25
New rumors point to a Steam handheld console in development.
If you've ever dreamed of Steam games on console, your dreams might be coming true.
During a school Q&A session, a student asked Valve founder Gabe Newell whether Steam would ever be considered for consoles (thanks u/Odysseic).
Newell responded "you'll get a better idea of that by the end of this year."
The student specifically asked about Steam games being published on consoles, such as Half-Life and Half-Life Alyx, not whether Steam libraries themselves would be ported to consoles.
As for when this announcement might happen, there are a few possible candidates
Valve Head Gabe Newell Teases Steam on Console
E3 2021 is the most likely candidate, particularly if Valve has new games to announce anyway.
However, it could also happen during the rebranded Steam Game Festival, now the Steam Next Fest.
Both of these are in June, though, which doesn't quite fit with Newell's tease about the end of the year.
Still, it could be just that: a tease.
Either way, Valve has an award-winning, landscape-changing library at its disposal, including DOTA and CounterStrike: Global Offensive.
It makes sense Newell would be interested in getting these games in front of more people.