MacBook Pro with Retina display owners might want to start looking for a new Twitter client because word on the block is that the company is ending development for its official Mac app. “Twitter for Mac is done. They won’t kill it outright, but no further updates,” according to confirmations from TechCrunch and its columnist MG Sielger. Last updated in June 2011, the official Mac Twitter app has been in dire need of an update to support new Retina-equipped MacBook Pro notebooks. In recent months, Twitter has been criticized for instating new API restrictions that prevent third-party apps from syndicating Twitter data — Wired has an excellent write-up on the ramifications of Twitter’s new API changes. With Twitter’s new restrictions and the possible end to its clean and minimalist Mac app, what will take its place?