[paulpauper]

payment and shopping integration and processing, higher quality video, expanded broadcasting, long-form content (a year ago Twitter said there were going to try longer character limits but I don't know what happened to that)

Twitter fills a niche.. it's not growing, but a pretty big one nonetheless. It's like classmates.com yahoo.com and other sites that are large, stagnant, but exist anyway because they fill a niche, have good advertising revenue, and have a lot of users.