I don't know if Mozilla is definitively boxed in at this point. Maybe there's an act 3 for them somewhere. I use their VPN and it's fine. They have a few other paid products.
They've repeatedly failed to leverage their Firefox userbase to build other products -- the mobile OS, of course, but also Mozilla Social, which they shut down without ever really launching it.
Eventually, that userbase is going to be too small to launch anything off of.