And Haruhi is a pretty sharp girl as evidenced by her conversation with the apartment manager and her observation of Yuki."It'll be a battle of attrition." -Haruhi Suzumiya
Kinda ironic for him to think that, and then have a few later episodes of actual detective work for Haruhi and Co."Impressive interrogating. You should become a detective." -Kyon
As for additional seasons or episodes, my theory is that they will have maybe a couple additional eps like the AIR specials that are shown later, or included on the DVD releases to fill in a few of the gaps. Considering that KyoAni is doing the remake of Kanon (26 eps?) and then they also still have Full Metal Panic as another possible project afterwards, a second season of Haruhi Suzumiya is possibly a year away. According to other people's observations, there should be enough material in the novels for a solid second season (a main story arc and enough stories to fill out 12 - 14 episodes), beyond that...