I'd say if your competitors are relying on looking at your roadmap to compete with you, then they're in trouble. Single features are often easy to copy but it's a losing battle if your competitor is way out in front of you and you're trying to copy them feature-by-feature.

Similar argument with open sourcing your product. Couldn't your competitors look at your code? Sure they could, but if that's how they're trying to compete, they're going to lose. Plus, their engineers will probably look at your code and think they can do better anyway ;-)