That's very true. lol
If you have a rooted Inc then you'll have to disable otacerts.zip if you don't want to receive updates (most custom ROMs that'll be made will do this automatically). If you don't and you accept the update, than you'll lose root access as the update will fix that. You would then lose the ability to root again until someone figures out how to gain root access on 2.2.
If you did root before the update, I'd suggest keeping it. It's more likely that someone makes a custom 2.2 ROM quicker than it'll take to gain root access on 2.2. In any case, the custom 2.2 ROMs will LIKELY be out beforehand, anyway.