There are fewer episodes for TMNT than I expected, but they probably want to stretch out the remaining season three episodes out for a bit longer. I don't know if they plan to jump right into season four after this season wraps up.
Actually there are 4 TMNT episodes left in September month. One of it includes one hour finale which includes two episodes total: "Annhilation: Earth!". I think some may be right that season 4 of TMNT may start in October though.