For many contexts, the two terms seem interchangeable, but my sense is that we prefer to use them under slightly different circumstances.
I take we might see to ideally express the possibility of using the faculty of sight to apprehend the object at some point in the future.
We might see lions on the safari.
To word the point simply, the lions are already there and the question is whether we will see it.
I take we might be seeing to reflect that the occurrence has not yet happened and this is why we are speaking in terms of probabilities:
We might be seeing a recession in the future.
The question is not whether or not we can see the recession if it is there. Instead, it is whether or not we will have a recession which we would then see. So we could say this means roughly the same as Were a recession to occur we would witness its consequences
But again we could definitely say:
We might see a recession in the next five years due to the tax policies of X.
and this would function with the same meaning as the above example.
I think adding the progressive modal expresses a lower degree of probability than the active modal statement and/or that the active modal relates to the successful use of the verb that follows in a more direct sense.
We might be seeing lions on the safari
sounds like one is hinting at something more than the direct modal.