So far during MoP we've had a content patch about every 3 months
Mop launch: 25th September
Patch 5.1: 27th November - 9 Weeks from launch
Patch 5.2: 5th March - 14 Weeks from 5.1
Patch 5.3: 21st May - 11 Weeks from 5.2
Patch 5.4: 10th September - 16 Weeks from 5.3
We are now 6-7 weeks after 5.4. The 3rd of December would put us at 12 weeks since 5.4.
I'm sure we'll all hear about what's coming next at Blizzcon, but since there's no sign of a content patch on the ptr. Could blizzard be cutting it a little close for a December patch?