Players have been doing the math on the ilvl system over the past few days and most come to the conclution that it will simply not work as catch up mechanic. BLizzard will have to overtune most of the 5.2 content to give the few ppl that have best gear + most possible ilvl upgrades some challenge. That means that content is even further away from most normal players and Blizzard needs to nerf content more than ever to allow those to take part later on.
I was reading topic from CG where he said that BLizzard might disable ilvl upgrade system in 5.2. Most of the players probably think that means they will just not allow players to upgrade their gear. But I think he was actually saying that Blizzard is thinking of totally removing the ilvl upgrade bonus from all gear. Pretty much a rollback and ppl will loose all their upgrades they used with their Valor points. Sounds crazy ? Yes... but still very possible.
So basicly - when 5.2 hits it might mean that every item will be rolled back to orginal ilvl without the ilvl upgrade. That is actually the ONLY way that BLizzard can lower the gap between the best geared vs the normal playerbase and keep the raid content balanced for both groups.
Either way. Ilvl upgrade system is probably the worst idea BLizzard has ever put into WOW. Its pretty much like every new system or changed system that came in with MOP. It was an idea that wasn't really thought through and will eventually lead to more issues than what it was ment to solve.