10 years is a long time
10 years ago, most of us were downloading over a 56k modem which gave you 30 something kbits at best. These days broadband has got to the point where many people have well over 1Mbit, and the reality is that most people have download speeds about 100x where they were 10 years ago. You need about 40Mbit for HD movies, and that could be here within 5 years. In 10 years we will probably have enough bandwidth for reliable HD movies.
Blu-Ray will fail for other reasons though.
1) Too expensive - both for players and disks.
2) Most people (tech geeks excepted) don't really feel the need for HD. I know a lot of people who have a full HD rig whose non-tech wife/husband accidentally watch and record shows in non-HD because they don't care about the difference. Most people moved from VHS to DVD for convenience not quality - rewinding the tapes, and jammed tapes etc. were a real issue.
3) Too expensive - so important it makes it in the list in multiple places
4) Region encoding embuggerance - worse than DVD.
5) Too expensive.
6) Takes over a minute to load a disk in most drives.
7) Too expensive.
8) Lack of forward and backward compatibility. An over the air update to your BD drive can make old disks unusable; not updating your BD drive by leaving it disconnected from the Internet can make new disks unusable. Most people aren't aware that the standard allows this, but it does, and it almost certainly will happen.
9) Too expensive.
You may not agree with all of these points, but they will all conspire to make DVDs outlast BDs in my opinion.
Personally, I moved from the UK to the US a few years ago, and I brought my significant DVD collection with me. When I walked into the biggest electronics store in Manhattan with a budget of up to $1k to buy a DVD or BD player, I said to the assistant my requirements. These were HDMI output and no region encoding. The only DVD player in the store that met those requirements was a Philips one for $40. It actually has pretty nice upscaling, and whilst I can see the difference when I watch something with an exceptionally high production standard in HD (like BBC Earth) - in general, I am totally happy with the quality of DVD on my big-ass TV. I'm certainly not going to replace my DVD collection with BDs like I did when I replaced my video collection. I'll buy the odd BD - like BBC Earth - but that will get immediately ripped on to my NAS so I don't get caught out with the forward/backward compatibility issues of the format.