I don't know if this is pointless or not but, I figured I should give you guys update for season 3.
Season 3 is confirmed and the director said that it will be the last season for Shana (But he did not specify when will they air it). However, they are re-airing both season 1 and 2 on TV right now. Season 1 on fall/winter, and season 2 on spring/summer. So a 3rd season might not come till next fall so in other words....a year from now.
For those who have watched Episode 4, the last ep of Shakugan no Shana S, the last part of the ep shows epilogue of season 3... But you need to read the novel in order to understand what Shana was saying at the end.
I know what I'm talking about since I'm up-to-date for light novel and plz dont ask me for sources since there wasn't any pictures/posters promoting season 3, instead there was interview transcript of director informing us that season 3 is confirmed.
For those who are wondering how season 3 is going to turn out, there is MASSIVE PLOT TWIST. You can read the spoiler where it explains what happend after season 2 (where we left off with Yuuji choosing between Shana and Yoshida)...