It looks like there is a provision in the law that says if you are at a range or competition, you may load a 10 round mag (that was purchased before April 15, 2013) to 10 rounds. Once you leave the range, you must load down to 7.
So, it looks like IDPA can go untouched. However, USPSA will lose limited and open divisions.
... and I see an opening! Just declare your house to be an IDPA stage, and load those standard cap mags up! Oh wait that's only if you're an "only one" in NY ...