Some dyno testing was performed about 10 years ago to address this topic of 88 motors. Back then there was no conclusive data the 88 made and any more power. So the issue was dropped with the allowance to shave early heads to match compression, but an output in the rule that a penalty might be created. In the early years of the series having a solid motor was more important than the pistons. So over time the issue was dropped.
Now 10 years on there are alot more properly built motors and it is time really revisit the idea. The 2012 wording is really a notice that there could be changes for 2013. Nothing will outlaw the 88 motor or 88 pistons, but if there is a clear edge then maybe some adjustments to either bring the other cars up or cap the 88's some how to ensure parity is maintained.