Some speculation here, seeing as 5.4 is looking like a mid-late August launch and even if blizzard does an unprecedented 16 week season that's still 8 more months of MoP starting in late August would mean a spring launch for the new expansion.
Or blizzard could be changing how they handle end of the expansion seasons. Instead of making it one really long season (37 weeks for WotLK and 38 Weeks for Cata) they could be breaking it down into two smaller seasons and with the launch of the last season give pvpers ilvl gear that would be around normal raiding gear, instead of right now it being just under LFR gear.