> Include these companies in the definition?
Surely not by name if they don't exist yet? And the rest of the bullets were pointing at why it's difficult to pinpoint them with additional terms.
> The easiest way around this is for a blanket catch-all clause such as "you have 1 year to start negotiations with us, after which this license automatically expires".
Which is great if you have some kind of legal foothold on megacorp, but if they're sufficiently legally isolated from you via intermediaries then additional clauses won't help.
> AGPLv3 is enforceable by contract law
In some jurisdictions (and copyright law in most others), but it doesn't magically hold third-parties responsible. It holds first-party users of your license responsible in a way which transitively affects third parties (copyleft being the mechanism). You might then claim that you could just do that for this contract too, but that's precisely my 3rd point above; doing so is unnecessarily restrictive to Elaborating on those restrictions, if randocorp is directly responsible for transitive users then they take on a huge risk whenever they have any customer because that customer might acquire megacorp as a customer at any point in time unbeknownst to them. If randocorp is not responsible for transitive users, then the mechanism for generating a connection between you and megacorp needs to be something like copyleft, but critically it has to somehow apply to contracts and interactions beyond copyright. At least it does if I'm understanding you correctly -- hypothetically, if you build a search tool, randocorp hosts the search tool, and megacorp buys searches from randocorp, would you like them to be targeted by the revenue sharing portion of your >X licenses? Anyway, assuming that's what you meant, copyleft by itself doesn't suffice, and you'd need something significantly more invasive than AGPLv3 to accomplish your goals.