I keep wondering too!
We are getting two with the Race to Space pack (grrr...wish we didn't have to rebuy Crystal McQueen - they must have made a lot of him, LOL). And supposedly have a date for the 3rd pack, but that's still 5 to go. Doubt we will get those before Nov when Series 2 comes out.
Will be interesting. At least the books are cheap, especially if you can get one on sale.