Interference is largely a property of the specific scheme. 5G schemes are better than LTE when comparing apples-to-apples (e.g. aggregate bandwidth on the same bands in the same geographic area), whatever comes after 5G will continue moving the ball forward, and the theoretical limitations on how much further we can keep kicking the ball are still out of sight.

Thus the question isn't what regulatory regime is best for squeezing the most out of LTE, but rather what's the optimal pace of radio communications evolution and how to achieve it. That's a drastically different type of question that almost certainly has a drastically different answer, or at least a much more complex answer.