I think they will tax and regulate it, and that won't kill Bitcoin. Why should it? It doesn't kill cash. When a company pays in bitcoin, that payment will be on their books and available to auditors. Salaries paid in bitcoin will be taxed at source. It'll no more evade tax than perks like company cars do.

We'll have bitcoin credit cards, and that will be an improvement because it will be more secure. Currently to pay with a CC the information you give to the merchant is the same info they could use to steal from you. With bitcoin, making a payment does not involve giving the merchant your private key. It's better.

We'll see things like payment processors and charge backs layered on top of the core protocol. I think they'll be optional. If you want the extra consumer protection that the CC charge back system gives you, it should be you who pays for it, not the merchant.

It will be interesting to see which of the benefits of bitcoin turn out to be due to "cutting corners" on things like consumer protection, which are due to efficiencies such as re-using the internet infrastructure, and which are due to avoiding fat-cat monopolistic self-serving policies of credit card companies and banks.