Most of my friends still play, and only play BlOps because "all their friends play it". I refuse to buy another MW2, so every time I come on, my friends quit playing BlOps and join me. It's not because I'm obstinate. It's because I don't have BlOps. I'm innocent!
http://blogs.computerra.ru/wp-content/uploads/2010/11/trollface.jpg
But seriously, get more Live friends. At Reach's peak, I'd see 25-30 people playing Reach at a time. I didn't always have friends playing, but people would come together to play in large groups. With BlOps, somebody's always on, but I've never seen more than 5 at once.