I like the idea of making the DVD available to buy at the theatre. First, you have to buy a theatre ticket to get to it, so the theatre isn't losing a dime. If you release the DVD exclusively in theatres showing the film you solve that problem. You might even stimulate some sales through enthusiasm.
I really think that those who will buy a theatre ticket to see a film on the big screen and those who will wait and see in later on DVD are two different audiences anyway. Catering to one group isn't stealing from the other. Honestly... when LOTR came out, and you went to the theatre, would you REALLY have bought the DVD (if you could) and taken it home to watch on your dinky TV with its 5" speaker?
The death of theatres... and movies in general... was predicted when TV arrived, when VHS arrived and now when DVDs are prevalent.