How does the 2013 baseball realignment affect fantasy baseball next year?

So, next year there will be two 15 team leagues with the Houston Astros moving to the American League. There will be interleague games scheduled throughout the season.

Obviously, it affects NL and AL only leagues. In my 12 team NL only keeper league, talent will be even more scarce in this league.

I imagine there might be fewer routine days off for some NL players as they can DH for a game in an AL park rather than completely sitting out. Right now, interleague play takes place in the early part of the season before the long grind of a season starts to have an affect.

So, what changes, if any, will happen in fantasy play?