Well, then you are going to be waiting for a long time as there is an average of about 400 days between releases.
Yeah, I wouldn't count on another update to the Mini anytime soon.
Maybe they'll bump them to Broadwell when it ships in large volume, if (and only if) the current Mini was designed with Broadwell in mind and they had to re-work it since Broadwell's release slipped substantially. Intel is having some execution problems. Luckily, they're stomping all over everyone else in performance, and still years and years ahead of the competition in lithography, so they're still doing okay.
But, even if they do that, it won't be until around this time next year. And I'd guess it'll sit idle till 2016 instead. And Broadwell is not likely to be much of a jump over current Haswell v2 CPUs in performance.
If you're not waiting on a Mini and you're thinking Mac Pro, then I'd definitely wait. The second-gen trashcan will probably be a much better setup. Thunderbolt 3 is why they're waiting to release a Retina (5k) pro display, I'd assume, since to drive the iMac's display, the current-gen trashcan would have to use two Thunderbolt cables to each one, and that's an ugly design Apple would just rather not do. Plus, you'll get a better generation CPU and whatnot.
If you're thinking laptop, then I don't know what I'd recommend. They'll probably rev them sooner this time around because of Broadwell. But, probably not till late-Q1 or Q2 of next year at the earliest.