Third, it's possible that the network will end up excessively centralized. If 90% of LN channel-value goes through a small handful of nodes, then that would be a real problem.
I find all this talk about centralization very strange, if you actually run a lightning node you'll quickly end up with 5-50 payment channels. Both incoming and outgoing. I've had a node running for a couple of weeks and already have 25 payment channels, most of them created by others connecting to me. This is extremely decentralized. Look at the network topology and how it's evolving, most nodes has a lot of channels in both directions and it's growing rapidly.