This is the result I expected when I first read about the new California law.

With a bit of luck, this story will get wide enough distribution that GOG will gain a bit of market share.

Sadly, if GOG gains enough new market share to have a material effect on Valve's bottom line, I imagine Valve's initial response will be a "most favored nation" clause in future publisher contracts allowing Steam to introduce offline, DRM-free installers for the subset of Steam games also available on GOG, diluting GOG's unique value proposition with a move that will nevertheless be hailed as a victory for consumers.