Yes, I bet there are already, or will be Windows 8 tablets which come with a built-in Blu-ray disc drives because a lot of the new Windows 8 Pro tablets have HD 1080P or higher screen resolutions, and a lot of Windows users still use DVD and Blu-Ray to watch movies at home, or on their laptop.
Plus, a lot of software and games you buy from a store still comes recorded on a disc since disc are cheapest to make, and more people know how to use discs for installing software.
To be completely honest, there really isn't much point. There isn't *that* much room to spare for one in a tablet and the space could be better used for a larger battery or hard drive space. There is also the alternative of getting an external drive to do the job.
If you're that desperate to have one, you can buy an external drive and just connect it by USB. That's what they usually do for tablets and ultrabooks that are missing the built in ones.
Pretty sure he's talking about regular CD/DVD size because I doubt people will want to buy a whole new disk for something they already own. Their new stuff can always be bought digitally. This is mainly to support their old things, along with any new DVDs or games they buy from retail.
I think the size of the computer would be smaller over time like the size of an iPad's 4 circuit board is about the size of 2 stick of RAM, but the battery and screen takes up most of the space inside an iPad.
Maybe an external case which also protects the tablet, and have a built-in blu-ray drive which can connect via USB, or wirelessly would be best.
The plastic Disc is still the cheapest form of storage since 1 DVD-R disc cost a quarter if you buy 100 DVD-R for 20.00 dollars or less. It can also solve the problem of running out of disc space on a tablet since Games can run off dual layer DVD disc which have storage up to 8.5 GB, or Blu-Ray with storage up to 50GB for dual layer disc and the memory card inside the tablet which is 64GB for most Windows Pro tablets can be used to save game saves.
For people who want to watch the most high quality video, Blu-Ray movies and soon 4K movie disc would be the best way to watch movies.
Also, it is easier to teach non-tech savvy people how to watch DVD movies since most DVDs just require you to put it in, and press play on a remote, or media player. I think some Disney DVD auto-plays when you put them in a disc drive, so kids can more easily play them.
