However, I can easily say, if you are watching movies on a 120" projection screen, at 1080p and even at 720p, there is a significant improvement in picture quality. Just as standard def TV looked bad when shown on 42"+ TVs, DVDs (including upscaled) can look similarly bad on 120"+ screens. I've got an Oppo DVD player, known as one of the best upscalers out there. It does a good job and animated films look great projected. But for movies with real actors, a quality Blu-Ray film blows away a DVD on a large projection screen.
Projectors are so cheap these days (a good 720p projector can be had for about the same as a good 40-50" plasma) that I wouldn't be surprised to see many more people adopting projectors. There's something very different about sitting down to watch a movie with friends or family in front of a 10' screen compared to a 42" TV.
I'd love to see Blu-Ray without the cumbersome, anti-fair-use (aka anti-"toddler insurance") crap. But I want the format to succeed because nothing else offers video quality that holds a candle to it. Some people think we'll skip mass adoption of Blu-Ray and go straight to digital delivery... okay as long as your net connection stays up. If you've got backup power and a library of disks, you've still got a movie night when the power goes out in the middle of a snow storm. With a physical disk and a player, you're not at the whim of your ISP, cable, or fiber provider when you have people over for a movie.