Ah, now I get it. The blog sample isn't just a different project, it's a whole different solution. Now I understand. This is the recommended approach, yes?
In order to learn the framework, I'm implementing a sample project I did some time ago. It would be have some core functionality, available to all tenants, with three modules (with associated features) of optional/premium functionality. Based on the documentation, it looks like the suggested structure is to develop the optional modules in separate assemblies from the core. Is this correct? Assuming so, do you happen to have an example of this (modules in separate assemblies)? In the Blog sample, the module is in core assembly.