Satoshi being the genius that he was I wonder why he didn't come up with a way that miners would auto-consolidate utxos from the utxo set as part of their normal mining process. That way, each address would only have a single utxo associated with it. Under normal circumstances. Kind of like an account based system but not really.
He didn't have to. As indicated, hard drive space is always going up too. Satoshi said something to that effect, and also something about all block headers or transactions fitting in a small space.
As for Opendimes, I like the concept, it's essentially a cold wallet or one of those physical coins with private keys / more advanced paper wallet. Perhaps for trading purposes, something like Opendimes would do when you have 0.01 BTC in several and you hand it over to someone else when buying stuff.
If I ever got one of those, I would of course sweep them immediately to my own form of cold storage.
Again, Opendimes do not use P2PK. Not many wallets today use P2PK. If you have an old address, it's probably not P2PK, and those will always be spendable in the future if you still have the private keys.
It's the P2PK public keys that we're talking about. Not addresses beginning with 1 or 3 or bc1.
I have no issues if there is no consensus ever about these public keys and nothing is done about them. They are likely to remain unspent in the next several decades and no one today uses these types of keys. With version 22 of the Core wallet released, we should also start seeing new Taproot addresses soon, maybe.