In earlier days there was a clear distinction between the big 6 and the rest of college basketball. There were years when a conference would be in a down cycle and it would be insultingly compared to an up-cycle A10 or Conference USA, but this never lasted. The big 6 just had too many advantages to stay down very long. Then the big 6 decided to get bigger and the Big East died, or at least only exists in a zombie-like form.
There are still 5 major conferences, but with all the shuffling, is there now a middle class of college basketball? While perusing the changes in at AP poll this week I noticed that 7 of the top 14 teams are from outside the big 5. The new American conference has 2 of those teams, and the zombie Big East has 2 more. There is also the always competitive A10, and recently competitive Mountain West. These conferences are more than just Gonzaga and the rest conferences, as they have multiple quality teams. They don't have the depth of talent that the Big 5 do, but they are not really mid Majors anymore either.
Much was made of the Mega conferences destroying the competitive balance as they sucked up every quality team in a major market, but so far the new middle class seems to be thriving in college basketball.