Twitter is a boat taking on water in a rising tide. Yes, the boat may be rising, but the boat is also taking on enough water that soon it will sink entirely to the bottom.
Every journalist worth their salt uses it, and it's essentially the public front for any media facing company. Sure, every day users may be contributing less, but it still seems to be a pretty meaningful megaphone for brands. I don't exactly see that changing: I don't contribute to Twitter, but I do consume the tweets of brands / companies / significant people that publish them.
