Encryption gets broken eventually as we get more compute power, and the current algorithms could have problems we're not yet aware of. IPFS requires every node to agree to your delete request (if I'm understanding it correctly). What's stopping someone from just vacuuming all the data they can until codebreaking catches up with encryption? Is there a way to remove malicious content? For example, if someone uses this…
What, no. Encryption gets broken only because we find weaknesses, not because compute power increases.
You can never straight up brute force a full-strength 512-bit key. That's just a fact of the universe. If the scale of your attacker is less than "literally the whole universe since the beginning of time", 256 bits will suffice against any future human developments.
But even less capable encryption is fairly strong. I would find it unlikely* that a single 3DES-encrypted message (a standard from 1981 with 112 bit effective key length) will be brute-forced, even with novel cryptanalysis, in your lifetime.
Even quantum computers won't help substantially for the capability in breaking a symmetric-key algorithm. Maybe** that 3DES message from 1981 can be broken with them, but any modern settings will not be.
*Unlikely as in less likely than not. I would be surprised if this happens, but the example here is to indicate that even obsolete messages don't have any constructive breaks against them, not that all 3DES messages are secure
**This would be a huge win for quantum computers, beyond imagining for now. But even with this huge win, you can't make such headway for a 256-bit key.