What will happen after the great reputation re-calc?
Most people will lose some reputation. Those that have made very subjective/controversial posts with a lot of up and down votes will lose more than those that made objective/noncontroversial posts.
Will I lose my close-vote privileges?
If you drop below 3,000 rep, then yes. You can query the database dump to approximate how much you might lose. They just handed out the latest dump from October.
Sam Saffron's post has a lot more information on the users that stand to lose the most, and includes the query which you can modify to give you an idea as to how much you would be affected. As pointed out by Joel in the comments, the full rep query is rather complex and difficult to duplicate in the datadump. But it should give you an idea.
However, as Sam's post pointed out, few people will lose more than 200 rep, and 200 rep can be gained in a day. So the rep calculation will likely set most people back by perhaps a day. You can prepare for it by working ahead, if it concerns you.