What are potential career paths after Product Marketing?

Oh my gosh - the possibilities are endless! The skills required for PMM are transferrable in so many ways. Like you mentioned, there's the product route that you can build on and either lead a PM or PMM team (or both!). The other obvious one is in the CMO direction - for this, you'd definitely need to expand your marketing lens into other areas of the marketing org (DG, ABM, field marketing, etc.) - you could start by trying out corporate/brand marketing or content marketing as an easy transition there. Other routes I've seen: enablement, product evangelist, go-to-market strategist, etc. Also, if you like the startup world, another less common but interesting route could be VC - a lot of times they look for people with product/pmm backgrounds at the associate level. 

I have seen product marketers move into various roles as their careers evolve. The PMM skill set is very applicable in most marketing roles. For example, a successful PMM should be able to translate insights into strategy, build power narratives that engage customers, and drive cross-functional alignment/execution. Therefore, you can apply those skills in a more data-driven way on the demand gen side, or you could use those abilities to have more ownership over product decision-making as a PM, or you could help sell more of a given product in a GTM role. I loved being a PMM because it offers you a lot of flexibility for the future.