Allow pluggable backend drivers for Function Execution

Most OpenStack projects have pluggable backend drivers for plugging different vendor's solutions / to promote vendor neutraility. For example Nova has support for HyperV, ESX, LibVirt, Xen and so on in a configurable, pluggable way. Can we add a pluggable backend system to Picasso so it could be used with other FaaS execution systems, for example Fission, IronFunctions, RawDocker, and so on. I know this is available in IronFunctions although it would be good from a community point of view to eliminate firm reliance on IronFunctions, of course IronFunctions could still be used if the deployer wanted to.