I am disappointed in some of the reactions this !! proposal !! has received, with some people apparently reading it in the most uncharitable way. It was a proposal that tried to address technical problems package maintainers and release engineering is facing, not some conspiracy to break the “gaming use case”.
As long as the kernel keeps supporting loading and executing processes with 32-bit code, they don’t even need to go that far. There shouldn’t be much stopping Valve from just supplying libraries themselves inside a container. In fact, that’s what the Steam Linux Runtime “Sniper” does.