All the heat issues with NUC and Brix will be resolved with Broadwell.
Apple IMO will make a better alternative to the competitors with Broadwell but it may lag in its introduction due to getting the Macbook and IMac the first chips.
That seems like a good possibility, but if the mini is going to lag on the lagging Broadwell that will be a long wait, so there is time for a Haswell interim step to happen this year (almost certainly).