Playing an FPS with console gamers on their clunky controllers is like putting on a botmatch and setting it to medium. No way I'm going to pay for that. Not to mention Halo 2 and Shadowrun doesn't look super appealing to begin with if you are on a platform with as many and as rich FPS experiences as the PC has.
I *hate* subscriptions. I've already got no less than five ways to use voice chat in games, and another five ways for IM'ing and finding games to play. If they are going to go for some kind of Gold BS, they better have the services behind it to boot. Like I said previously:
A) Discounted Microsoft Game Studio PC catalog.
B) Fast, no wait file server that hosts demos, mods, and other large files, akin to something like FileShack or FilePlanet.
C) Dedicated voice chat channel-NOT peer to peer, but a server side thing that is always up with a low (8-10) max people per room.
And more stuff I can't think off of the top of my head.