As for the option to turn off in-game ads... well they could always remove that option. I think the player base would have a different standpoint with the future of the game in dire straits.
The biggest trick is one that a lot of web sites are learning these days: make the ads inoffensive. Not "unobtrusive," but also not "glaring, in-your-face annoying."
I use adblock on a lot of sites, but some I frequent I turn it off for (they had requests that I do so where their banners normally would show) because I do want to support them
and because the ads aren't huge load-time additions and don't flash and pop and overlay in ways that make them irritating. They're there, off to the side, and if they catch my eye because they look interesting, I might be persuaded to check them out. That's how ads work best: pique interest, catch the eye of your intended audience, and inform them there is a product they might wish to buy.
Jumping out and screaming at them the way many pop-ups work is what gives advertising a bad name. I think a lot of quiet ad space could be very effectively sold in a game without offending anybody who wasn't going out of his way to be offended.
