I cannot believe we're on the 41st release in this line (actually 52nd if you count the smaller issues seen on Kobold Quarterly last year). We're always looking for feedback for the series--especially what spells you'd like to see next!
That is a likely possibility but I don't see it happening soon. A second Compendium would definitely include all of the aforementioned KQ articles (these would be beefed up as they were purposefully smaller than the normal pdfs).