So, most of you know the chances of the Pokemon 2017 season going on, and what might go on in the Standard format, but I don't think we thought about the Expanded format for 2017. Here's what I think will happen
Looking at the XY era of Pokemon cards, we saw many expansions out in the card game. But which expansions will drop into Expanded. From what I know, XY, FlashFire, and Furious Fists are sure to drop to Expanded. But Phantom Forces, Primal Clash, Roaring Skies, and Ancient Origins are still yet to be known about. The BREAK era will definitely be in the 2017 season, though. From my view, a Yveltal/Krookodile-EX is inevitably falling to Expanded. But other strategies you guys know may also drop.
I'm thinking that Dark-type decks will reign supreme in the Pokemon TCG Expanded format, having 3 Yveltal (XY, BREAKthrough, Air Crash Promo), Darkrai-EX from both BW-something and BREAKthrough/point, and Dark Patch, but Fighting-Type may also reign supreme in the format.
Special Condition-inflicting Pokemon and Trainer Cards may also reign supreme in Expanded. Standard trends with Expanded variations may also work well.
Good luck, Pokemon fans!