Ryan Singer talked about how they (don’t) deal with roadmaps on the Signal v. In short: roadmaps are a bad idea because they can create uncertainty, false expectations, and guilt. My favorite argument against long term roadmaps is the uncertainty.
Say we have features A, B, and C we want to build. We don’t know if A is going to work out as planned, and what that would mean for B. We don’t know if we’ll have a eureka in the bathtub one day, and new idea X will suddenly feel much more important than B or C. Or we might start building out B, only to realize that it’s not what we want or it’s harder than we thought and want to bail on it.