You should check prices on the 2GB SD cards not the high end ones because the disks usually contain that much or less. Most AAA games only have the game INSTALLER on the disk, and still require you to download the game in order to play it.

30 second search at 100gb (modern AAA games and the biggest Bluray)

Bluray is $10 a disc, microsd is $8 and you get 128gb and can get bigger media, which doesn't exist for Bluray.

That doesn't account for mass production, fewer people care about physical media with every passing year.

Physical media will still exist, but it won't be optical. Opticals advantages over cart just don't exist anymore. You don't include a $80+ part on the bom when less than 5% of your users want it and that 5% can get a bog standard usb device that can be had for $10