It’s not just cost, it is time. Nodes will eventually need 32gigs of ram. The question is does that happen in 2 years or 10? A determined attacker today would be competing with a lot of people for block space and so they wouldn’t be able to fill every block with lots of utxos, some blocks would be full of large data blobs and few utxos. In 10 years a low end laptop will have 32gigs of ram so no one will care. In 2 years a 32 gig machine is likely a server grade set up.