Years ago, a VP at Sony stated that BluRay would be the last optical format. I suspect the next prerecorded media format (if there is one) will be simlar to SD cards.
I never fell into the overpriced Blueray scam. The quality of DVDs is just fine. It was blown out of proportion and it costs them no more to make a blueray disk than it does a DVD. It was all just hype to hyper-inflate the price.
And I think you are right... They should have just went to SD card format a longtime ago. The player can be the size of a cigarette pack with no moving mechanical parts to wear out and a whole library of hundreds of movies can be stored in one shoebox.
I think a flash drive would hold more bytes than an SD card. But if they can put films and TV series on flash drives or even on SD cards, I would start a collection immediately.