I doubt even Epic are under the illusion that it will "bring people back" to the game. (Which is a bit of a silly way to look at this anyhow, as people who just don't like the game - just don't like the game [dur].
It's not quite that simple, when we're talking about this group of people, then we are talking people who do like UT and this kind of gameplay, but who for various reasons do not like UT3 in particular.
I'm one of thouse people, and belive you me, my mind could easilly be changed, all it would take is for them to fix some of the things that are missing or broken from this game (things that past versions of UT had, mainly).
For me its the Instant-Action menu that needs to be fixed to bring me back (sadly this is not happening right now, so i wont be reinstalling yet), others will have different hangups (some of which may be fixed now, and then they will probably start playing again).
The only group you really can't depend on, are the people who want it to be exactly like UT2kX'es gameplay and wont accept anything else, thouse wont be comming back i'd wager, for the rest of us, if enough, or the right things gets fixed, we'll want to play it.