There's an easy fix...
...Stop charging a subscription to play online.
Immediately MS will have a marketable reason for people to flock from Sony's Playstation network to Microsoft's Xbox network. Furthermore, it shouldn't be as painful for MS as they charge most a subscription to use MS Office - Which is something Sony can't do.
There's absolutely no reason why anyone should have to pay a subscription to play online.
"But muh subs"
- Wall Street