Understand the following is all hypothetical.
Suppose you were a member of a basketball shoe duopoly trying to manage risk and market share for the long term in a duopoly relationship. What kind of regime of dominant teams would you want to encourage?
To hypothesize an answer, one first has to make an assumption about whether duopoly members might want to stay a duopoly, or want to kill off one of the members, and become a monopoly, or add more and become an oligopoly.
Historically, in my recollection, most monopolies eventually default into oligopolies of two to six members. There are lots of reasons for this that we don't need to go into now in order to make a reasonable assumption.
Historically, I can recall few if any oligopolies that have defaulted into monopoly, but that does not mean there are none. It just indicates my anecdotal sense of tendency. Again, there are lots of reasons for this that we don't need to go into now in order to make a reasonable assumption.
Lets be conservative here and stick with historical tendency, or at least my anecdotal recollection of it. Let's assume that path dependence in the future favors the currently hypothesized duopoly choosing either to stay a duopoly, or choosing to default into an oligopoly of up to six members. Let's further assume, for the sake of simplicity, that duopoly is the regime that persists for the foreseeable future simply out of path dependent inertia. This last is probably an unreliable assumption in the long term, but almost any assumption is unreliable in the long term, so let's go with it for the sake of simplicity in taking our first baby steps in thinking about this stuff.
Under this assumption, what regime of dominant teams in a four region NCAA tournament might most likely support the perpetuation of a duopoly?
Hypothesis: I reckon each duopolist would seek to establish four heavily talent laden teams with each one having a high probability of being a one-, or a two-seed team in each region by the end of the season.
Duopolist A loading four teams with top talent, and Duopolist B loading 4 teams with top talent, would go along way statistically to ensuring that a Final Four and a Final Two included Duopoly teams, and that a Duopoly team won the ring. Dominating the Final Four and Final Two and winning most of the rings would go along way to perpetuating the duopoly members' market positions and would overtime, make it a high probability that one, or the other, duopolist almost always landed the "next Michael Jordan."
Not saying this is how it necessarily is.
Saying this is a hypothesis that might be interesting to fit with data.