Ah yes the classic forced overselling scam...
You can not even buy the single UHD disc mate, You are forced to buy and pay extra for the bluray and online copy. And UV was shut down who will pay for this 10yrs from now? No one will pay for the terrabytes needed so yes i predict like you they will be lost and you will not own them.
Second point, The disc has a superior quality and uncompressed. Thirdly when the internet is down how do you stream 4k media? Its really really dumb to not buy physical media and the way 35mm film works ia the resolution is about 6k. So if say you like the Matrix the UHD is a true 4k rip you like me might say this is a good investment because if they do say in 10yrs time an 8k version the chances are it will be an upsample from software and deep learning from the 4k master.
Very very few will get a true 8k master i suspect, So if you want something forever simply check real or fake 4k website and consult thier list of real or fake 4k. And guess what? Its also a scam because a lot of new films like the £99 Harry Potter 8 disc set are all fake apart from the first one. So they hold back on many new films by simply upsampling the bluray to 4k and they dupe buyers into thinking its real 4k. The scam is that this enables them at a later date to go back and remaster the 35mm negatives at real 4k or 8k and sell the boxset again for another £99. So this is why anything true 4k that is on the IMDB top 250 i will buy the physical UHD because its the best thing to do as a consumer. When paired with a 2020 OLED screen we are in my opinion at the peak of cinema for the format 8k will be perfection but 4k is close enough for me.