Go to google and type "magic what's happening". It should take you to a link on the wizards page for online play. In the bottom right hand side of the page there are listings of tournaments. If you look at the RTR block tournaments, it's a good indicator of what you might see post rotation, but remember that there are still 2 sets that come out M14 and Theros. Esper is heavily figured.
M14 will not impact the meta a lot, so far only scavenging ooze looks to be a game changing card. I could be wrong though. I'm actually looking towards BG. Golgari has a lot of strong cards in rtr block. vraska, abrupt decay, varolz, lotleth troll, deathrite shaman, deadbridge chant, gaze of granite...