Wasn't twitter also measuring success in number of users and growth, marginalizing their losses? For now it seems like they're still only a picture-sharing app

Wasn't twitter also measuring success in number of users and growth, marginalizing their losses? For now it seems like they're still only a picture-sharing app that's popular right now. Obviously they're doing a lot to secure this position, but I wonder if they'll be able to maintain user's engagement for a longer period of time.