If they don't have an HD TV, and they try to play the DVD on their TV through a PS3, what will happen.
The Sony PS3 utilizes HDMI. If your TV doesn't have an HDMI input, you're not going to be able to connect (unless there is an HDMI to AV adapter out there).
As for the PS3 being the ideal way to watch Blu-ray, there are a few disadvantages..
* You can't upconvert standard DVDs like other Blu-ray players will
* Menu navigation is awkward
* You can't control the PS3 with your universal remote
* You can't send the kids off to play video games while you watch a movie!