Recording ability has nothing to do with buying movies. I didn't say it did. But the reason VHS stayed alive as long as it did was because it could record and DVD couldn't. Once DVD could record, THAT made VHS fully obsolete. Why continue to use tapes that can wear out when you can use discs that don't wear, as well as don't have to be rewound?
Likewise, when BD recorders become commonplace, they'll no doubt record better quality than DVD, which in turn will make DVD obsolete.
It's called common sense. Try it some time.