@clacke for some things, I think that paying people to work inside existing distributions can also work; it is e.g. already possible to pay somebody to work on maintaining specific debian packages past the time the official support for a certain release has ended (and probably also way past the official *upstream* support has ended).
It has to be managed carefully, but I believe that Freexian / Debian LTS is a good example which could apply to other cases (and is probably completely not suitable for others).
The main advantage here would be that the results of such paid work would be available also for other people, and thus they could be less expensive for each individual customer.