There are a couple more minor but welcome additions in development. Twitter is working on the option to support Live Photos from iOS devices as GIFs in case you want your snapshots to be that much livelier. You'll also have the freedom to reorder photos in the app after you've uploaded them. You won't have to worry about botching an event tweet by posting the photos out of sequence, to put it another way.
The company has good reason to turn its attention to DMs after spending so much time on public-facing features. Remember, Mark Zuckerberg outlined plans for a privacy-focused Facebook with more emphasis on chats and other "simple, intimate" spaces. If Twitter wants to lure people away from those spaces, it has to make DMs more compelling than they are today.