Some Blu-rays are sadly suffering from disc rot already, it doesn't look like they last as long as CDs or DVDs, but the ones failing now are most likely either due to temperature/humidity conditions and bad printing process, either way, I don't think Blu-rays will last as long as 100 years. They are listed to last about half of a CD/DVD, so around 50 years if stored properly.

There is also some strange reports about PS3 Blu-rays that look pristine being refused to be read by the PS3 since some time now, I also read they could still back it up on some programs without a problem so not likely disc rot, so I dunno what is happening to some PS3 Blu-rays discs, maybe some games batches got inferior printing quality and are suffering faster than they should when put against an also aging PS3 laser.

There is a conspiracy theory that some PS3 updates where making the PS3 unnable to read certain game discs, because the reports of some games having problems are bigger than others, but as other people copies can still be read by their PS3s that is just indeed conspiracy theory, as it would affect basically everyone with those games, which is not the case.

Anyway, I should really think about backing up all my games, specially the PS3 ones.

What happens when disc drives are no longer produced? They don't last 100 years. 

Storing a game on 5 different flash memory devices, and then transferring it to newer technologies when they become available lasts indefinitely. 

I hope your right.

Why can't the next PlayStation and Xbox consoles use SD or SSD cards? Aren't those cheap to put games on?

Nope, even before the AI boom flash media was much more expensive than optical media. But especially now it is more expensive. That's why Nintendo's physical media is so expensive. 

Having said that, I think it is more efficient in the long run to have rewritable flash storage, even if it is more expensive than read-only. I still have working SSD's that release nearly 20 years ago (80GB Intel ones I bought used off Ebay 10 years ago.) 

Sony, Microsoft, and Nintendo should allow people to make drm-free copies of their games x years after release. But they wouldn't do that because then that makes selling remakes/remasters harder, and in Nintendo's case where they treat their IPs like Disney does, it makes limited releases harder. Plus people would share games more, reducing sales. That's the negatice of closed platforms. 

I think the model would work if they priced the games higher. People would be more willing to pay more if they got full ownership, and that would make up for the marginal impact on sales. The alternative is that piracy will be far more appealing and more people will do it, reducing sales anyway. 

It's getting harder to fix the RAM and memory shortages without destroying data centers. Most data centers aren't even necessary to begin with. AI is disrupting the economy, increasing harmful emissions, increasing noise pollution, hogging drinking water, and driving up electricity costs. AI at it's current state isn't worth the money.

My PS3 stopped reading my Gran Turismo 6 disc, and I think eventually it started having issues with other discs as well. When it was only the GT6 disc, I think rotating the console to some weird situation until it could read enough of the disc to start the game worked as a workaround. Anyway, if I recall correctly, GT6 used a dual-layer disc, so I'm guessing it's harder to read for disc drives. I'm guessing hence you might first have issues with only some games, and as time passes, you might encounter issues with other games as well. To no surprise, as soon as I replaced the disc drive lens, all discs could be read successfully again.

tl;dr: It's probably a disc drive issue.

There are reports of people testing the same game in 3 PS3s and they still not working, and even so, they could still back the game up, it's really strange, kinda of random even lol

If Sony insist on going digital, could they at least make online play free?

OK, I guess that doesn't sound like a disc drive issue then...

I'm going to guess the answer is 'absolutely not', because PS+ is probably a huge moneymaker, and subscriber numbers would probably plummet if they did that. Games included in the subscription are definitely a bit of a draw, but I bet most people don't care about them enough - I bet most people are in it just for the multiplayer.