Of course it won’t.
This is just the next step in killing third-party apps. Twitter doesn’t have the guts to just end them outright, so they’re just gradually inflicting passive-aggressive wounds over time to quietly shove them into the sunset.
We’re all just one compelling feature away from leaving our third-party apps on our own. For some of us, this full-archive search will be that feature. What’s next remains to be seen — I suspect direct-message enhancements may be — but I bet third-party clients will lose half of their users within two years without Twitter ever having to explicitly kill them.
We won’t even be angry at Twitter — we’ll move to the official apps voluntarily, and we’ll look back on all third-party clients like we look back on Tweetie, vanity link shorteners, and third-party image hosts today: as relics of a quickly abandoned past before we all started using Twitter’s better, newer features. You’ll see.
(Via friend-of-the-show Manton Reece, a great developer who Twitter lost along the way.)