BlueLock - When will software pricing move to pay-as-you-go like cloud computing?

Cloud computing providers like BlueLock know that it would make a lot of sense to pay for software the same way you bill your clients – per-usage or pay-as-you-go. This pricing model is reflective of the utility-based model of cloud computing, the hottest trend in IT since the personal computer some say, where clients are charged each month based on the amount of infrastructure, power, compute, etc that they use. So what about the software licenses? Yes, cloud computing providers also lump that sum into the monthly cost, but it doesn’t cover the full upfront charge for the software because that wouldn’t be fair to the client. One of the biggest benefits of cloud computing is the clients ability to pay only as they go, with no upfront capital costs, and in a good world that means they don't have to lay out costs for the software either.

Federal agencies who are now taking on the role of cloud service provider and other cloud service providers themselves are beginning to ask software vendors to price their products in a pay-per-use model so it makes more financial sense for them. The current license agreement requires service providers to outlay the money upfront for the enterprise license. In a cloud model that means the provider has to take on all of the risk by paying the upfront cost.

Do you think this is fair? Would it make sense and be feasible for software providers to charge for their software on a per-usage monthly basis?