I think you will never be able to pay coffee with bitcoins, when (and if) people really start using it (which is what we want). Unless you are willing to pay very high fees.
I think you should be careful to distinguish Bitcoin the currency and Bitcoin the payment network when you speak because on this matter what you can "never" do is quite different depending on which you're speaking of I know you know this but the language makes it unclear.
Off-course, I meant that the coffee transaction does not end up being written into the block-chain, but you *still* are paying with bitcoins (through other means). After all, the block chain is just a distributed time stamp server. There is no need to put everything in there. So, if you can achieve the same goal (pay) through more efficient means, it is ok.
Thanks anyhow for the clarification you made which is very useful.
Best regards,
ilpirata79