What time limit? The blog post says jQuery 1.9 will be supported even after 2.0 is released, and that the two APIs will be the same.
I'd also like to point out that this concern only comes into play 2 years from now. We are not intending to drop support for oldIE forever, but we do want to make jQuery smaller and as efficient as possible in the newer browsers, and leaving all the oldIE code in as we progress past these browsers wastes time.
What jQuery 2.1 feature can't you live without?