The problem with this thinking is that Twitter is not a software tool that needs to be improved. It's a TV show that has ran its course and is declining. Hollywood knows how to deal with these problems: they end the show, and replace it with a new one. The problem here is that Twitter is an infotainment studio with one single show. And Wall St will not let it run as a startup anymore, incubating early stage new shows like Periscope.
I reject the metaphor. Just because a tool does not gain new followers (heh) anymore, doesn't mean it should be killed. It would be interesting to know if Twitter would be profitable if it is just put into maintenance mode.
My point is, Twitter has value for me the way it is. I don't personally see any reason for changing it. Of course, that's not a reasoning that Wall Street would agree with.
