I would like to see a juggernaut type game mode, where one player randomly spawns with bacon and whoever kills them gets their bacon. And to keep the bacon moving, if you don't get a pro kill or kill 10 bots in 1 minute, you loose the bacon.
Interesting idea, but would need some other elements to make it work. The game is very much balanced around Crossfire. If you implement game modes like juggernaut or deathmatch straight up, without a lot of other tweaks and elements, you will end up with nothing but Assaults running around. Some classes lose a ton of their usefulness when you take bots and turrets out of the equation.
Now you're thinking with portals... err bacon. This is a pretty good idea actually, make it so that the bacon holder is always visible on the map so he can't hide, and he has to do X damage to the ball to bring down the shields just as the bot would.