I am pretty sure I am going to buy Kompakt to use with at least one or two Kontakt sample libraries (I do not need the additional features in Kontakt).
Since Kontakt 2 is coming out, I do not know what NI is going to do with Kompakt. If they are going to discontinue the $129 upgrade and push everyone into buying Kontakt 2 (at a much higher price point) that would be a reason to buy Kompakt now.
On the other hand, if they will offer the same deal on Kompakt 2 (that can play Kontakt 1 and 2 samples and include a better library), maybe it would pay to wait.
Any thoughts on the very important topic?