I am sure we would all prefer large instant rebates (or just plain lower prices - the effect is the same), but none of us here are in charge of setting Best Buy's sale policy. And we aren't privy to their future sales plans. So all we can do is wait and see.
If you are considering making a purchase, and want to know whether or not to wait for a non-MIR deal, I would suggest just going ahead and making a purchase the next time they go on sale, with or without mail in rebates. Best Buy rebates seem to be pretty reliable, unlike CompUSA's.