I too am fascinated by Bitcoin and still in learning mode. I think there's one important distinction to add here though. Credit cards can charge 2.5% because they're
awesome Some guy in Arizona can set himself up online, sign up for Stripe, have no set fees, and accept a payment from someone in Germany (or NY or Australia) that afternoon. That's amazingly empowering and 2.5% doesn't seem to bad for the people running those rails to collect (fraud, global movement etc)
So let's not come at it from "credit cards and payments are a bloated gouging industry" I'm not buying that and it also is too merchant focused (vs consumers who really decide what a merchant will do in terms of payments) Now, there are some really interesting fringe cases that Chris touches upon that can open the door for Bitcoin. Micropayments are broken when it comes to credit cards. It's not the %, it that's "+ 30 cents" that is brutal. So Bitcoin could play a roll there. There are disbursements and marketplaces. I suspect TaskRabbit would probably like to have the ability to move money from buyers on their platforms to the TaskRabbiter's with a reduced payment friction than today. There might be 5% margin businesses (Chris' example sounds like the founder of Dwolla) that really are motivated to drive you to Bitcoin.
So what happens over time is Bitcoin focuses in on those areas where it has a strategic advantage over cards and ignores those where it doesn't. It uses that experience to become a legitimate, scaled set of payments rails. Solutions are implemented so that consumers are comfortable with using and paying with Bitcoin. Then at that 5 - 15 year mark it's ready to take on mainstream payments. Assuming issues like fraud and settlement and wild fluctuations are worked out.
EDIT: I am definitely thinking out loud and on the fly so am ok with some serious rebuttals.