I’m curious what they mean by ‘free’, since the details seem sketchy from what I can find - but it’s certainly a weird turn-of-face by Valve. Historically they hated outside developers use their engine. Thechineseroom had a real struggle to let them use it for Dear Esther, I recall, but multiple indie games have used it since (Insurgency, Nuclear Dawn etc.).
I don’t see it changing much, though. It’s not a particularly flexible engine in the same way UE4 and Unity are, and the art pipeline has (historically) been absolutely awful.
If it is actually free though, that could be very interesting.