Does anyone know if the "relay network'[0] addresses this? It seems like it should, and I think most of the major pools/miners are using it already.

0. http://bitcoinrelaynetwork.org/

It would be great to have a decentralized relay network! Right now this is a centralized bandaid solution, which is unfortunately necessary because of many well-known vulnerabilities of Bitcoin's p2p layer.

E.g.

- Tampering with the Delivery of Blocks and Transactions in Bitcoin https://eprint.iacr.org/2015/578

- Bitcoin over Tor isn't a good idea http://arxiv.org/pdf/1410.6079.pdf

I would think so. Eclipse attack relies on a node selection algorithm vulnerable to selecting malicious nodes. So as long as the nodes here don't ever become malicious...

The next logical attack in this scenario would be to spoof IP addresses, which is much harder.

I think BGP hijacks have actually been done against bitcoin.

I agree. You still run into the same problem because you have to assume these nodes are not malicious. It's even worse because most pools and miners use it. If any node is malicious, everyone will be affected.