There's a strong possibility of a 5.5, giving them time to wrap up any loose ends from MoP and start to more full seed the next expansion's storyline within the game in the form of, potentially, scenarios, quest chains, and the pre-expansion events. If 5.4 would have to last 8 months or more to see us through to a new expansion launch, I can almost guarantee we'll see a 5.5.
(Source on 5.5 possibly existing: http://www.blizzplanet.com/blog/comm...aria-patch-5-2 )
Also from that same source, they discuss odd number patches as 'content' patches, with even number patches being 'raid tier' patches. Take that as you will.