Yeah I agree with Tom, this could get pretty messy with registrations and updates and email verificiations etc.
The easiest way I think we'll have to do this will be to register it "for" our customers. We should already have most of their information to register with, and then let them know how to get the software and help them get it installed and tell them how it works etc. The hard part will be getting it installed and tutoring them on the usage if they've not used many programs before, but most have at some point done something on the computer so it shouldn't be horribly bad.
This way they get their own registration yet if they have problems they can always come to us for assistance. I don't think that's going to be all that big of a deal myself. I know I won't have the time to try to keep up other people's shops, especially multiple ones and still handle my own and web building at some point too, so it will be a good advantage to them to do it themselves, and we all know how easy it is so it shouldn't be too hard.
Nothing says we can't create their themes for a price, and nothing says we can't give support for a price and nothing says you have to charge for any of it, it's up to you. But I don't think reselling CC software is a viable option myself. It will just get too complicating and hassling to have to keep transferring registrations.
You know the real problem here won't be the shopping cart software, it will be the photos lol, that's where most people are going to have the most difficulty I think. The software is so easy to use, and with us to guide them it should be quite easy and maybe even fun for them, I know it is fun for me. But ... photos are a whole separate issue especially if they aren't nearby where you can get them off their camaras for them, or actually take the photos for them etc.