I haven't noticed them going out of print, but I do notice that the prices for new releases on Blu Ray during their first week are significantly cheaper than if purchased later, even through eBay.
For example, most Blu Ray's carry a $40 MSRP, retail for $22 - 30 and can be purchased on Tuesday - Saturday of their release week for $17 -22.
So, while they will still likely be available once you get your player, if it's a title you KNOW you're going to want, then it might make sense to buy right away. Lots of Blu Rays come with 3 discs, too - the Blu disc, the DVD and a digital copy. So, in the meantime before you get your player, you'll still be able to enjoy the content on DVD.
