Using HD-DVD is a VERY GOOD IDEA for all those points you mentioned, so I totally aggree with you about that! There is one problem though, those drives will be old-technology then and very slow in comparison. You can't simply use though those old drives because of this, you need to improve the technology. There is a chance that some other format or Bluray can be cheaper by that time.
People are complaining about the size of dvd in 360 and then speculate about "digital download" only media in the future. Its uncomrehensible! I mean given that the dvd size is barely enough now, future games will be dozens of Gigabytes and do you honestly expect people to download all those data? The bandwidths will not be THAT good, they will probably increase 3-4 times in the next 5 years, which is still a pain in the ass if you'd like to download a 20-30 GB data! (with 10 mbps, it will take ablout 10 hours for the best scenario! Plus many potential problems).
Playstation 5 vs XBox Series Market Share Estimates
Regional Analysis (only MS and Sony Consoles)
Europe => XB1 : 23-24 % vs PS4 : 76-77%
N. America => XB1 : 49-52% vs PS4 : 48-51%
Global => XB1 : 32-34% vs PS4 : 66-68%
