Personally, I think interest in the FRM will drop once it goes to two levels. One of the main attractions (vs PRM and CFA) was that it was only one exam. Granted PRM is actually 4 exams, but you can take them whenever you want and also get an exemption from the first two.
It would be interesting to see the recent growth rate in applicants for both FRM and PRM, of course discounting the anomalous growth in FRM this year due to the transition to two levels.