first off: I really like to see quake servers be populated again, thanks to steam-release(won't debate here on loadouts etc).

I think what is important to motivate those new players to stay for more then 4-5 hours of playtime, is to build a newb-friendly community around them. don't know if it's possible with steam, but I remember when I started quake 3 in 1999, there was mplayer.com. you had a big lobby where all players meet, with icons next to their nickname(displaying ranks). the players could open their own rooms from the lobby, there were tournaments etc...

next important thing would be: offer them HATS! for example an own 'store' to individualize the visuals of quake: blood and gibs(rating would only get higher for THIS certain dlc), different weapon skins probably borrowed from differend quake incarnations, different anouncer voice, texture packs for maps(gothic, industrial etc..)
this would produce extra-profit to pay more dev's etc..

probably would be a good idea too, to have atleast 1 'classic' server online in EVERY game-mode to show new players that there is a 'step above' the servers with loadouts.

in the same time would be good to change the name of 'classic'-ruleset to 'competitive'. that way new players would understand why they get owned on those servers, not because it's classic=old=bad, but because it's competitive=more demanding.

just some thoughts and to all the hardcore-players, it won't affect you negatively because all the irc-pickups etc are still there and working, now we only have to take the chance to get as many new players to try 'competitive' quake ))