VRZone has gotten their hands on a leaked Intel roadmap that shows Haswell is in no rush to leave. According to the desktop roadmap, we can expect Haswell to stick around until Broadwell shows up in 2015. Haswell will get a refresh in 2014, but that refresh will likely only boost performance marginally.
Intel doesn't really need to rush out Broadwell simply because they face next to no competition on the desktop CPU front. The mid-life refresh will likely consist of a small speed bump, which is only really important for locked CPUs. The USB 3 bug will also likely be fixed by then, if not before. We also expect an updated chipset, probably the Z97, to be released around the same time.
Of course, mobile could see an update to Broadwell sooner, though it won't likely be more than two quarters ahead of the desktop.