We've been testing this change for a few months to make sure that, broadly speaking, the vast majority of current customers are willing to pay for the new functionality. We don't want to even try to charge for things that customers don't feel they're getting good value from.

There's obviously heterogeneity, though, and we'll be as reasonable as possible. If this would be really disruptive for your business, or if you need more time to plan a migration (if you don't think Billing makes sense for you), or something like that, I'd be happy to connect you with the team -- we could extend your current pricing through the end of 2021.