It's incremental development like any other. Its hard because running real time markets is always hard. If you want them to have extra resources you piggyback on, just subsidize their costs up front and then take the unused resources. The user doesn't even have to do an extra step. This is easy as pie.
Reality is a pretty big hurdle.
By this logic, PayPal should be micropayment central. We have all the infrastructure we need, we just don't have any demand. All rights reserved.