Yes janol, everything but twitters official apps will fail. This is specifically aimed at client apps. It is a way to specifically Target client apps because it deals only with DM's which are mostly viewed through client applications. And specifically you said even tweetdeck, I would say especially tweetdeck. They control the largest amount of users outside of the official app and they have been attacking these large clients for some time now. By directly targeting DM's only it should be obvious to everyone why they are doing this. It's presented as some small change but the fallout for clients will be insane. You can't spin the news in a way to make it sound positive or even necessary. It's going to cause a storm of user confusion, deleted apps, bad reviews, complaints to customer support, uncertainty as to why they have to regive permission and religion their accounts. And if you app holds multiple accounts, your in for a nightmare. No one will want to go through putting all their info back into the app.
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