Elon Musk cannot milk Tweetbot users as much, so, goodbye 3rd-party. Predictable.
Twitter could also start charging app devs for API licenses, or restrict 3rd party apps to Twitter blue users if they want to change things up.
It already does, which is why Tweetbot, Twitterific and the others had to shift to subscription models.
Ironically, because those third party apps pay for API access for all their global users, and Twitter Blue is only available in about five countries, cutting off third party clients will have an immediate negative impact on Twitter’s revenue.
As noted in the thread, the agreement itself includes a tiny cap on damages, but there are legal factors which plausibly could nullify the effect of that cap.