The problem with any sort of alt-currency whether it's Flattr points or some cryptocoin is that it's always going to have the insurmountable barrier of indirection that ensures it's never going to have more than the fraction of hard-core users that are willing to buy into it. Signing up with Flattr or Coinbase to even access these alt-currencies is such a showstopper when we need a solution that can go mainstream.
I think the only solution that has a shot is enabling and improving the UX of spending plain ol' USD with the same motion we thoughtlessly buy groceries.
For example, a specific low overhead micropayment channel. It's kind of silly to pay the full cost of things like refund ability and fraud protection on a $0.005 purchase.
Without this, I don't see how micropayments will ever be a thing.
People often bring up the mental overhead of a la carte pricing for things like individual Netflix shows vs $12/mo. But I think they're also looking at it through the lens of the current world where you can't even price something below $1 if you're going to accept anything other than cash.