But what I do think is inevitable, if Bitcoin is successful, is that people will demand zero-trust, blockchain-style, incorruptible pseudonymous ledgers as the lowest stratum for ownership of all their financial assets, not just BTC.
No, I understand you think this, and you're certainly not alone. What I don't understand is why you think this.
You may say that you
hope this, to wit, that "everything" turns into a sort of open-source thingee. This is fine, and that I can understand. But practically, people do not in fact want or desire, let alone demand, to tinker with things that require specialist knowledge and experience.
Most of Europe is heated on gas boilers. People aren't currently demanding that they service these themselves. On the contrary, people are mostly demanding that nobody is allowed to service the things themselves, and use certified specialists instead. This because the risk of explosion from incompetent maintenance is perceived as higher than the benefits (many and numerous as they may be) of tinkering with the thing. What can you do in the end, make it "more efficient"? You can't make it more efficient by hand, it's an industrial product.
People aren't demanding equipment to do their own dental work. It's not that some clever chap couldn't arrange a bunch of mirrors so you could drill your own teeth. It's just that people do not wish to do this. People used to fix their own cars, as recently as twenty years ago, back when it was still useful and needed. Practically nobody fixes his own car now. People used to cook their own meals. They don't anymore. People used to elect their own representatives. They mostly don't anymore. Heck, for that matter people used to invest their own money.
People, in general, will demand that they be left alone. Yes, they want a point of control, and Bitcoin provides that superbly. But once they've got that point of control they are no longer interested in pushing control further down the chain. Investment is fiduciary by its very nature, expecting people to trust the investee but expecting them to not trust at all any intermediary is an exercise in mental divergence. Before people will demand zero-trust ledgers people will stop investing at all, for lack of trust.
That said, certainly zero-trust ledgers make excellent sense. But NOT for people. They make excellent sense for the very specialists, those people trusted by others to handle their asset holdings. Consequently, such an implementation is not useful done haphazardly, by a bunch of mostly stupid, mostly irresponsible, mostly clueless self-appointed devs. And when I say mostly stupid, mostly irresponsible, mostly clueless self-appointed devs, my mental blueprint is the people currently maintaining bitcoin-qt and the rest of the "core infrastructure". People like Taaki, Maxwell, the whole gang that actually shipped bitcoin with unencrypted wallets, people who actually put "address signatures" in but the output looks
like something a goose shat and so on.
Currently the demand for something like that is practically zero, for very good market reasons (which mostly boil down to, for MPEx itself, MPEx is zero-trust already). When that demand increases to the point where further implementation makes sense, it will be developed by those people involved, for their use. To best grok this, think of that Seinfeld episode when Kramer finds "better paths" for the fire department to take and the fire department is duly unimpressed.
Then on top of that, you might get different kinds of providers catering to different scenarios: IPO handlers, fullservice brokers, discount brokers, trusts, etc., all coexisting on top of the same asset-tracking blockchain.
You don't get to be the authority in a market just because you think of the market mentally in your head. You don't get to be the one who decides what gets built where just because you flew over the land and saw everything tiny down there. Most markets worth the mention have intrinsic authority, and you will be employed to work in furthering their goals rather than walk in there with all the brashness of youth and start telling them what's what. There's no IT CEO in all of the banking industry, and I will be muchly surprised that there ever will be an IT CEO in Bitcoin finance. The role of the developer in this field is subservient, no matter how grandiose he may feel himself in his inner core. (And for that matter, the notion that there should be IT CEOs in IT is still hotly debated - but mostly the consensus is "no").
Within the various service types, undoubtedly we will see the network effects and survival of the fittest that you describe in your other post, and your company might become the premier entity in any of those segments.
You seem to be discussing the recent past as if it were some sort of distant future. This boggles, are we speaking of the Revolution here or something?
But for risk mitigation purposes and for those who enjoy getting their hands dirty, the option would (should!) always exist to verify & transfer ownership of assets at a blockchain level, without intermediaries.
You do verify such, that's why you get the signed receipts as it is. A blockchain on top of this would actually add delays and costs which aren't in fact necessary: you already have exactly the same thing, a cryptographically signed receipt. There's no practical difference between the stuff in the blockchain saying you own some bitcoins and your saved receipts saying you own some S.MPOE.
MPEx has the advantage of not making you wait ten minutes to an hour for it, because it's passing down to you the advantage it enjoys of not having to contend with unknown and potentially unsafe peers. These are advantages you will be fighting to conserve, even if the programmer in you would love nothing more than to resolve problems that are sexy, for fame and glory. Fact is, not all sexy unknowns wish to vigorously copulate with programmers.
In fact, if experience is any guide, most don't.
). 
