I was concerned reading the initial post. My desire for C2 has steadily declined since its announcement. First major blow was the html5 only exporter, so I decided to wait until the exe exporter was around before trying it. And then subscriptions...I am more than happy to help support the program and the devs by paying, but a subscription model is a huge turn off for me.
But I am heartened that you are intent on finding a good solution. The idea of buying two years(or whatever time frame) of updates for whatever price you set is one that really interests me. Being able to actually own something I bought and be able to support you chaps too. Would not be against paying for specific exporters either, or specific additional plugins/behaviours etc.
I am not sure what you could do to make the free version less appealing that buying the editor and updates without being so minimal as to be ignorable, or seriously impacting to the point of not wanting to use it.