I think you're right, the roles will exist for some time. But I think we'll start to see more and more overlap between engineering, product management and design.

In a lot of ways I think that will lead to stronger delivery teams. As a designer—the best performing teams I've been on have individuals with a core competency, but a lot of overlap in other areas. Product managers with strong engineering instincts, engineers with strong design instincts, etc. When there is less ambiguity in communication, teams deliver better software.

Longer-term I'm unsure. Maybe there is some sort of fusion into all-purpose product people able to do everything?