They probably could fit the rest of SHnY into a 26 episode season, but I doubt it. It is more likely that more money is made in the long run if the series is split up into 2 13-episode runs (franchise will last longer as opposed to 1 full season, just think Full Metal Panic).
KaneDragon: The next anime after Kanon is Lucky Star.
As far as when SHnY will be aired, I do hope it's next Fall season. Makes sense as Kanon will finish at the end of March; 2 months or so for preparation of Lucky Star, and air that during summer; a wait of 2 months to prepare the series to be aired in the Fall season. I can hardly wait for any sort of confirmation from KyoAni
.