I don't see the lack of a regulated exchange as a show-stopper for mainstream adoption. I remember when people were generally uncomfortable with PayPal because the whole idea of an online wallet that wasn't provided by a bank just seemed unsafe. It was pull of eBay, the killer use case, that overcame that in the minds of everyday people, not regulation coming along and making it safer. Online wallets added value.
Imho, Bitcoin is and will continue to be an interesting niche until someone comes up with something truly compelling to do with it that you can't do with traditional currency or banking. A regulated exchange is nice for traders and financiers, but it's still just a boring old exchange... another friction ordinary consumers have to overcome to walk the blockchain life.
I've never been that bullish on Bitcoin because I don't see why the mainstream, developed world would have much demand for it. It certainly has it's uses, but they are limited. I suspect the number of people transacting in Bitcoin are far out-numbered by the people who are mostly hoarding Bitcoin, which illustrates it's lack of valid use-cases.
I once thought that bitcoin's usage as a secure decentralized database, not as a currency, would be the source of some major use. But there are no big results here, so now, not so sure.
Imho, Bitcoin is and will continue to be an interesting niche until someone comes up with something truly compelling to do with it that you can't do with traditional currency or banking. A regulated exchange is nice for traders and financiers, but it's still just a boring old exchange... another friction ordinary consumers have to overcome to walk the blockchain life.