If you're talking about a first person shooter, I think it's entirley possible. I am having a hard time coming up with the specific reason for implementation, but it is a good idea to keep players that are AFK from being useless blobs of lag.
I think that this would actually be easier than it sounds. According to Valve's observation of players in multi-player games, most will not only stick to 1 specific map, but also take similar (if not the same) attack paths most of the time. It may become a bit less predictable with more complex games such as Team Fortess, but for something like BF2 or Counter Strike, I think it would really be just a matter of tracking the players movements, their KD ratio, their accuracy, and patterns of movement/reaction time.
With these combine together, you could take a bot AI template and modify it according to the players skill.
Actually I think you may have something here. Better hurry up and make it before I do.
EDIT: Oh, and as an extra advanced piece if you feel so inclined, the skills of players can increase and fall in certain areas of the map, so it would be good to track their accuracy/kill rate in different zones.