Unfortunately, I think the answer is that it depends.
For a vessel-based licence, you can only put a licence on that fits the vessel length requirements. It would depend upon what it is that you're trying to diversify.
There are other examples of diversification. For example, in a salmon fishery we have area-based licences. You have to pick one area and one gear. You could, however, stack licences onto a vessel so that you could go to different areas and fish for a longer period of time. That's an example, and there are other examples, so you would have to be careful.
With a party-based licence you would have more flexibility, but you would need to think that piece through. I think it's a good consideration.