I would be surprised if they don't drop at least as low as 20th or even all the way out of the polls.
Even without a good Purdue, it's been considered the best conference in all of D1 men's basketball for large portions of the last several seasons. The only issue is that none of the top teams can finish the deal once they get to the Final Four. When Maryland joins next year, they'll take the spot of having the most recent title from Michigan State, since Maryland won it all in 2002, while Michigan State and the rest of the Big Ten last won it all in 2000.