However, I would agree that it is "as good as dead". What killed 20% time? Stack ranking.
Google's perf management is basically an elaborate game where using 20% time is a losing move. In my time there, this has become markedly more the case. I have done many engineering/coding 20% projects and other non-engineering projects, with probably 20-40% producing "real" results (which over 7 years I think has been more than worth it for the company). But these projects are generally not rewarded. Part of the problem is that you actually need 40% time now at Google -- 20% to do stuff, then 20% to tell everyone what you did (sell it).
I am a bit disappointed that relatively few of my peers will consciously make the tradeoff of accepting a slower promotion rate in return for learning new things. Promotion optimizes for depth and not breadth. Breadth -- connecting disparate ideas -- is almost invariably what's needed for groundbreaking innovation.