In essence, if mining incentives go low (and unspoken in title: If transaction volumes stay low so that transaction incentives are also low), then a 51% attack becomes trivial over time b/c miners drop out.

So, either we start using bitcoin a lot, generating significant transaction fee revenue to keep miners in, or it's doomed to an inevitable compromise.

So they are attacking bitcoin as a stable store of value, but not necessarily as a currency. Is there a road to 1000x more daily transactions? I don't know. It's currently more like a blue chip stock than a currency or asset.