And frankly the Bitcoin P2P network is quite latency sensitive, new blocks need to be flooded as fast as possible to minimize miner losses to orphan blocks, so it's unclear to me that the entire Bitcoin network will ever run behind Tor 100%.
It's quite latency sensitive now, but the low hanging fruit in terms of improving that hasn't even been touched yet.
Start with a new block message that only includes transactions hashes instead of full transactions and you reduce the amount of burst bandwidth needed by a factor of (size of a hash)/(average transaction size).
With a bit more work miners can broadcast most of the block in parallel with hashing so that the amount data they need to rapidly propagate once they find a valid hash is tiny and constant relative to the transaction rate.