Juli Clover, writing for MacRumors:

Twitter Blue will include an “Undo Tweet” option that holds a tweet for a set period of time before sending it out so you can choose to undo it, and a “Reader Mode” that makes it easier to read long threads.

I might go for something like this if it was a way to support a premium AI that could be used in apps like TweetBot and Twitterific. I use the official app (alongside both of the much better paid third party apps) only because Twitter denuded their (decidedly better) third-party clients. Still hurts though.

Twitter Confirms Plans for ‘Twitter Blue’ $2.99 Monthly Subscription Service