Going further, my suspicion is that deflationary effects and the rise of transaction fees will be such that, even for those who are sufficiently tech-savvy, it will be advantageous for most, if not all, people to access the network in this way.
It will only be advantageous for the thieves, inside and outside the bank, who eventually loot the accounts of anyone foolish enough to entrust their bitcoins to a third party.
I don't disagree with your assessment but it doesn't make the "federated" outcome I outlined any less likely. Put another way: if Bitcoin goes mainstream and a few banks start offering Bitcoin accounts, my money would be on them capturing the majority of "retail" users before long.
I mean: if Cyprus was not enough to trigger queues outside banks in Italy, Greece and Spain this week, what would detach the average person from their affection for lending their wealth to banks from whom they may not get it back?
I submit this is the desired outcome of anyone advocating that Bitcoin remain deliberately limited such that most users will not have the option of maintaining control over their own funds.
That is a fair point: the Bitcoin network, today, is wholly unsuitable as a mechanism for storing and transferring my parents' money (my usual test for whether a technology is ready for non-technical mainstream users). That's not to say things won't change, of course.