Mike, like I said a hundred times already.. I don't care how it's solved and am willing to accept almost any rule change as long as I keep my Bitcoin sovereignty. That's all I care about.
In short, even if Bitcoin becomes enormous, I can't see a time when hazek is unable to check what the rules are, even in the unlikely even that he is forced to rely on SPV mode.
BTW Bitcoin sovereignty doesn't mean I just want to be able to validate what rules are used when transactions are validated and blocks created and added to the blockchain. It means that these rules also can't change for me without me downloaded a new set. Right now it's extremely hard to do a hard fork if you don't have near complete consensus because of the economic ramifications. You need almost all users to agree. But once you take away full clients from merchants and regular users, rule changes can happen at any time because you don't need them to download anything anymore because they aren't actually validating anything anymore. Yes you can probably still spot a rule change, but you can't affect it by being part of the network and refusing to download a new client threatening a hard fork.
But hey, as I said, I don't care how this is achieved. If a light client can give me the same sovereignty, I don't care, as long as it does. As long as I have to give my explicit consent to a rule change, I'm happy.