I'd guess at PCB sales (commission), component sales (commission), maybe a prototype assemby service (commission), upselling features within CM, upselling to AD, charging to jailbreak designs. Plenty of ways of harvesting a few dollars from the willing, without unnecessarily pissing off the userbase. No idea if it'll cover the costs or be profitable, but that's all part of being a company...
Since I'm hoping this is substantially based on the AD codebase, code, documentation and support should be where the money goes.
As far as I can see, Altium have taken far worse gambles over the years. This one kinda makes sense to me, even though I'm not a likely customer.
Edit: Documentation. Altium, FFS, you do need to sort the documentation. AD-levels of ineptitude really won't work for a more casual audience. Knocking out a few videos of 'how to' is one thing, but actual documentation, kept up to date and in sync with the code, would make CM stand out from the other packages. You know, sort of look professional?