Well, of course, there will always be good reasons to wait - for certain price drops, new models, ... whatever.
However, if you have wanted the K-3 for so long and can't shake the feeling that it may help you take your photography to the next level, plus you happen to have the spending money to actually afford it, why on earth shouldn't you get it?
Coming from the K20D (which certainly was no slouch in its day and is still a good DSLR), the K-3 will be much more than some incremental upgrade - I trust it will blow you away, after you've learned to get the most out of it. And that will still be true even when some new flagship model is out. Besides, having a family myself I know perfectly well how soon your precious photo budget can be gone for good if you wait too long. You know, cars and washing machines can break down any day, and any day spent without the K-3 is a day spent without the K-3.
No, I'm not pleading for irresponsible spending. It's just that having skipped so many models in between you sound like someone who deserves a little reward.
I upgraded from a K-7, which I'd shot for nearly five years, and am absolutely loving my K-3, best camera purchase ever.