I think it's clear that Bitcoin has a few niche uses, though broad acceptance seems unlikely because non-reversibility is so unforgiving.
Do you really think this is the big hangup? I think you're implying a bit more. It's the non-reversibility in conjunction with wild west non-regulation and internet anonymity. Cash is just as non-reversible, but we have regulation (in the US) to protect transactions regardless of the medium used.
Edit: actually, I think I'm just splitting hairs. It's the combination of what I'm saying above that makes BTC so non-reversible, yeah?
Actually, I was referring to bitcoin itself, not the exchanges, nor the usage of an anonymity network like Tor in conjunction with running bitcoin.
While there is precedence for a global "undo" when a bug was found and 2 billion coins minted, there's no one that has the power to undo any specific transaction. It's like running a bank without a backup of the main ledger, and no possibility of ever having a backup. While you'll never lose a copy of the blockchain, there's no backup in the sense that an old copy can't be restored if you find an erroneous transaction, whether it be a mistake, theft, or whatnot. Non-reversibility is both a feature and a bug, and for most transactions, this "bug" isn't worth the risk. Sure, you can build other things on top of bitcoin that provide this feature, but then you're no longer talking about bitcoin.
Most people want reversibility in their transactions, whether it be credit card chargebacks, returning spoilt milk, or nabbing the pickpocket and getting your money back. Perhaps more instructive is to examine one user group that loves non-reversibility and other features of bitcoin: the black market.
Though the possible anonymity (technically pseudonymity) aspect tends to be highlighted, non-reversibility is also a prerequisite when buying prohibited items (ie Silk Road). Someone could require ransom in bitcoins, and then they know that the bills won't be marked, everyone can see if ransom has been paid, and no risky meeting place has to be arranged. Bitcoins are also perfect for unregulated money transfers between countries, and since there's sometimes no legal way to reverse a transaction between countries. Bitcoins for country-to-country money transfer is basically like a Hawala network, which is the primary money remittance system used in many parts of the world (and is, of course, illegal in the USA):
http://www.treasury.gov/resource-center/terrorist-illicit-finance/Documents/FinCEN-Hawala-rpt.pdfThere's a reason that Nigerian spammer/scammers are in Nigeria: there's no way to undo a transaction, or prosecute the scammer.
From most people's point of view, bitcoins "features" don't represent progress, though they are clearly useful in limited cases. Then again, is the world better off with nuclear weapons and nuclear power? Perhaps not. I even think that the advent of agriculture was not necessarily good for humans, forcing us out of a hunter-gatherer lifestyle and into a sedentary farming lifestyle that we aren't well suited for. But bitcoin is here to stay: it's up to us to figure out what the hell to do with this new and disruptive technology, and hopefully we'll find productive uses over the coming years.