> But you're relying on your chosen cloud-provider staying around for 30 years.

Yes, and I recognize that the company existing, or at least that product existing for that long isn't incredibly likely. But I think the fact that there's 3 products from massive companies like Amazon, Google, Microsoft, and 2 from smaller ones, dropbox/backblaze that lasted 10 years means that at the very minimum ~20 years should be considered as realistically possible.

And honestly, if we're willing to assume whatever we're storing isn't worth them storing for longer (let's say against your will) - then you should just rekey it anyway yourself.

But I'm lazy, and again we're getting to near 15 years for some of those services now.

> The number of tech companies that have died in the last 30 years easily exceeds the number still standing [citation needed].

I don't disagree with your premise that the company/product you pick isn't likely to last for 30 years - however I don't think this specific statistic is the correct one to evaluate this with, given the wide range of tech companies with differing products, markets, financial situations, regulations, the many startups that are effectively designed to be acquired, etc.

At the very least, I don't think it's fair to compare Google/Microsoft/AWS to "insert latest crypto based file storage startup" in terms of long-term viability.

No cryptographic scheme remains unbreakable forever. If what you want is permanent protection, cryptography is not the solution. If people are encrypting things expecting that encryption will never be broken, they're misusing encryption.

The point of cryptography isn't to keep secrets forever, it's to keep secrets for long enough that by the time those secrets are revealed, they are worthless.

I can tell you that journalists aren't worrying about that most of the time. It's very much outside their threat model in the majority of cases, as it should be - there's no way to feasibly predict and protect against cryptographic risks 30+ years from now.

In that case the volume of traffic such a communication medium would need to handle is likely small enough that you can bump the key size higher to ensure greater longevity, currently past the lifetimes of those involved, and accept that transmitting data will take a small fraction of time longer.

If extreme security is needed it’s time to turn off your computer, leave your cellphone at home, don’t tell details to colleagues who do not have a need to know, and maybe resort to dead drop methods so even you don’t know who the source is yourself.

Being pedantic: RSA is a cryptosystem, not a protocol, and the parameters that were used in 1980s RSA encryption look nothing like the parameters used in today's RSA (in part because they're much larger now, but also in part because we now know about all the weird things that happen when you choose non-standard exponents, primes that are too close to each other, etc.).

RSA is also not typically described as robust, for those reasons.