I'm not in strategic management, but I've talked to people here about similar issues.
First, "strategic management" is extremely broad and vague. You need to be much more specific about your research interests in order to evaluate whether they are really well-studied or not. Anything relevant will be considered well-studied if you are asking about something generic like that.
Now, I'd say any topic is publishable. What makes a paper publishable is not the topic itself. There are much more important factors, like the contributions you are making and the strength of the evidence you are presenting. If the topic is well-studied, of course it's going to be harder to make a relevant contribution, and there are many researchers who know a lot about the topic. So, you should be ready for the challenge. But if you are able to write a strong paper about the topic, you should be able to publish it.