Well, here's my attempt at a september format list. I say attempt because no list can be 100% accurate and because I'm mostly reporting from experiences in either my games or observing local tourneys.
Now then...let's go.
Don't know if I should go adding stuff to the banned category here, but it seems we get something banned every format. Most people are suggesting either Trunade or Monster Reborn as options for the banhammer.
For my part, I would probably just skip the bans, as I haven't been too sharp predicting bans.
Hyper Librarian should probably go to 1, since it's too insane to be left at 3.
Formula Synchron is on the same boat. Lowering it to 1 won't kill it, since it's needed for other synchros and it's a helpful monster. But at 3 is just too insane, especially when combined with librarian.
LSS Shi En is probably another guess for limited. One is all you need anyways to completely dominate.
Solemn Warning is another card I would like to see go to 1.
Trishula will take it's rightful place in the limited list for the TCG so it can be the same as the OCG.
I have seen some people debate about either limiting or semi-limiting Pot of Avarice, since it's going completely bonkers with Plants and Tengu. However, I would somehow see this on the semi list for some reason.
Reborn Tengu will NOT be on the September list, so people have to stop saying it will be. The formats are based on the OCG meta mostly and Tengu is still a TCG exclusive.
Doubt any Blackwing stuff will be there, but if anything's hit it might be Vayu with a limit due to the great use of Graveyard Feathers in the OCG.
For semi limit it's tough to see what can and cannot go. But if I had to pick, it would possibly be either Tech Genus stuff or perhaps Doppel Warrior since it's also going berserk. A semi would slow it down a bit but not really make the deck useless.
Perhaps a semi on Duality? I don't know.
Damn...making this prediction is hard.
People speculate on the return of BLS - Envoy of the Beginning but I doubt it will return. Then again, we have all been surprised before by a random move.
As for unlimited, it could be anybody's ball game.
But then again, I'm just guessing all the stuff from the list. Who knows what might happen in September?