Yes, and no! I have a loose plan, but full disclosure... There is also a chance that the roadmap will be cut short: Lately I have felt very burnt out with the project, and after 3~4 years I might simply not have it in me to pour many more months of work into the game! I know that's not what anyone wants to hear, but I'm just being realistic, heh: We'll have to see how things go.

In more concrete terms: Immediately after the anniversary update I want to look into Steam Cards/Items and see if those would make sense. In the greater scheme of things, I want to get started working on a DLC, adding even more maps.
If the DLC does happen, it will keep me busy for quite a while; so anything else would have to wait until after.