Paul Haddad 
Step 1. Kill the most popular class of clients of an API, one of the few that could afford to pay money for access.
Step 2. Start charging for the API.
But hey at least 1 weeks notice this time…
A Twitter API->nMastodon API bridge server that covers a handful of the most popular API calls would probably be really popular. Yeah I know it's an easy migration but people (myself included) are lazy, the less work to move over the better.
The real big brain move is announcing that you are going to move to a paid model without announcing what the prices are.
You have a week to deal with edge functionality on your app/website breaking, you can wait and hope for the best or just nuke it right away. I know which choice I'd make.
People have been asking if this means Tweetbot might come back. Well it's a possibility if the new pricing is reasonable and ... HAHAHAHAHA
Adam Williams@paul i can’t wait to see elon find out how bad this will hurt his platform. twitter for sign in or sign up on web? yeah it’ll vanish overnight. integration with popular apps like discord and platforms like xbox and playstation. yeah somethibg tells me they won’t pay either. twitter is going to be dropped form relevance so fast