Bluray will take over from DVD at some point, but when this will be will depend on many things. The pricing of Bluray discs is determined by the retailers - looking on Play.com you'll find Iron Man on Bluray for £17.99, with the DVD coming in rather close at £14.99. This should be a no brainer, and it's far from the only example. Look on Movietyme.com and you'll find many region free Blurays for £10-12, and some below. Anybody who wants to show BD in a negative light regarding pricing will always pick the most expensive places, which are usually supermarkets and high street media retailers. Find the cheapest places and it's a very different story.
Cast your mind back a couple of years and many of you, if not all, were paying £15-20 for a new release DVD. I know I paid £18 for Shaun Of The Dead. It was well worth it as I knew I'd get my moneys worth out of it, and it's definitely worth the same on BD when it appears.To replace your most watched films, I can't see why people are moaning about an average £15 price. Lesser watched films are worth £10 or less to me, but any I watch on a vaguely regular basis are worth the money for audio alone, without taking into account the picture quality.
Those of you who're opposed to the current high street pricing should speak with their wallets - order online from more reasonably priced outlets rather than a quick glance when you're buying the groceries.
I suppose all this comes down to the value the individual puts on something, but usually many people tend to be a little unreasonable in their estimations. Let's not forget that Bluray has fallen in price far quicker than DVD did within the first few years of it's release. This can only mean good things for the future of BD.