@glyph @chrisjrn @webology @offby1 @hynek @coderanger FWIW, I think there's absolutely a way that this can be a graceful changeover -- it's not necessary that moving away from Fastly would be disruptive to PyPI users. It's not a given that they'd pull support without sufficient notice such that it requires a panicked/immediate response.
They could just be like "Hey, in 6 months, we're gonna stop providing this for free" -- there'll be work to do but it can end up being fine?