I'll be getting the Xbox One in June barring all the games I want somehow coming on the PS4. And I'll be getting the PS4 a year or two later. I decided to wait because there's really no reason to rush to buy one right now due to the lack of quality games at launch and the lack of a game library in general. Watch Dogs, Quantum, Destiny, and several other good games will be coming out by June or so, but I don't expect many particular exclusives to be out by that time. Still, I'd rather play a game built for next gen on a next-gen platform rather than a current one, unless we're including my PC.
I look forward to another adventure in the Halo universe come September as well.
As for my 360 gamertag, I'm allowing my Xbox Live account to stay inactive for a few months for the first time in 10 years. I just don't see any purpose to keep it on since I'm not really actively using it and the only games I need to catch up on are either on my PC which I'll do over Winter Break, or on the PS3 (Last of Us, Beyond Two Souls, Tales of Xillia, etc) which I'll likewise do over Winter Break. Plus, the Xbox Games for Gold lineup for this month isn't very exciting and the Black Friday deals didn't really have any Xbox Live cards for a reasonable price.
Since I mostly play RPG's and singleplayer or local co-op games, I shouldn't be losing out on much. But I will turn it back on around the time I get an Xbox One most likely, unless the Games for Gold for the 360 plan turns out to have a better lineup, then I'll oblige myself by activating it again. If I do, I'll be sure to put down my gamertag, since it won't be online ever until I do.