The whole schedule is a mess right now becuase of unbalanced leagues and interleague play. They'll get it fixed when they expand by 2 teams and go back to the old system of interleague weekends, but they can't expand until they figure out new stadiums for the A's and Rays. The Raiders moving to Vegas opens up the A's to have the Colusiem site and the Rays are actively looking for a new stadium site right now.
I'm more than ready for 32 teams with the Mexico City Luchador's and the Montreal Expos.
I don't think MLB will ever go backwards on interleague play, for better or for worse. I think it's more likely that sometime in the next 20 years the NL will add the DH and MLB will schedule even more interleague games.