I don't believe this is an attempt to snag player bases from regular MMOs, but more like propose a new experience for the GTA franchise, which so far, seems to be pretty well made.
They respect what made the GTA franchise successful , graphics are the same but improved (You won't all of a sudden be able to play a disney char in GTA..
[You must be logged in to view images. Log in or Register.]).
It doesn't seem time sinks will be huge. More like, go fuck around with your friends and blow shit up whilst you keep cops off your corner.