I'm gonna say No, A. Because it's been done before. B. There's much better DLC to be made/had. Everyone has already had this idea because it's not original...just ripped from the Red Dead DLC that was the exact same.
Cops and Robbers has been done before, but I think it would definitely be a lot more entertaining than zombies.
As for ORIGINAL dlc, I've heard Casino/Gambling, crazy ass gambling missions. Though to me that just isn't going to happen, anything that involves/could involve making large amounts of money won't get implemented. Rockstar doesn't want us earning our money, they want us using the micro-transaction/cash cards.
As much as I hate to admit I'd like it a Mafia/Casino DLC would be dope. The Mafia Crews are the most over used unoriginal crap online, but I'd want a mafia DLC just for badass suits/clothes we got jipped on. Seriously...3 suits Rockstar?
Another idea I had was a Hitman DLC, though I suspect most people would be too sissy for this.
Basically, you can hire another player as a hitman for someone that pissed you off, say - your arch enemy. Maybe keep it level based so it's fair, like you can't have a level 120 go after a level 5 for a hit, that's just silly.
Once the hit is arranged the chances of you ending up in the lobby with the target GREATLY increase. One hit per person. (You can't have 12 hitman go after one dude.) Sure, a lot of sisses would just disconnect from the lobby immediately and run away, but something could be implemented to prevent this - say if you run away from a hitman instead of trying your best against them you get sent to bad sport for an extended stay, or you lose a significant amount of cash. Or something funny like you're forced to wear a hot pink shirt with the words "Sissy" on it. lol.
Last idea would just be some DLC that included the katana. When was the last time we saw it? San Andreas right? Maybe even some in-depth sword fighting mechanics. Doesn't seem like it would be too hard to do, and it wouldn't have to be that intricate, just simply included the katana, all though maybe the player would have to work to get it instead of just being able to buy it. (Though rockstar would probably make it available for Microsoft points regardless.)