Mike Isaac, writing for All Things D:
Therein lies Twitter’s goal: A rich, consistent Twitter experience for every user. When the hammer drops and Twitter changes its guidelines, those apps that can’t deliver this consistency will no longer be able to integrate with Twitter. The most likely candidates to go first, according to multiple sources, fall into two camps: Third-party-client apps which essentially reduplicate the Twitter stream — such as Tweetbot, Echofon and Osfoora — and news reader apps like Flipboard, which re-renders Twitter data to create a different visual experience of a tweet entirely.
Marco Arment links to both Isaac’s post and MG Siegler’s, and explains why this consistency won’t roll out to third-party clients:
Maybe the reason promoted tweets still don’t show up in the API, and therefore still aren’t displayed by third-party clients, is that Twitter never had any intention of monetizing the timeline outside of their official clients, because there won’t be any more third-party clients soon.
It would be entirely possible for Twitter to send promoted tweets and Cards to third-party clients, and keep that revenue stream open. But, curiously, they haven’t. That’s a frightening prospect.