For a customer-facing CSM (as opposed to a team-leader Manager of Customer Success), the most likely career path, apart from staying in CS, would be into Sales at some point, capitalizing on their domain expertise. That ultimately could lead them to a CCO -Chief Customer Officer position. Or they could move into CS team management, in which case the career path could also run all the way to CCO.
Either way, at some point, a shift would be required from being an individual contributor over to serving as the leader of a team.
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