Before/after SS because art + tech, or somewhere in the Child timeline because implied connections and I love TP too much for my own good.
It don't think it will be before SS as this is legend of Zelda not legend of Hylia. I don't think they would make this game Zeldaless and the first Zelda existed in Skyward Sword so the game would take place afterwards.
There is also the existence of Ganon who came after Demise was destroyed.
The reasons this isn't before OOT are quite numerous but I'll list just a few:
Ganon is in his beast form. They could retcon it in that there was a Ganon before the Ganondorf of OOT but the presence of koroks makes this placement even more unlikely as they evolved from the Kokiri which existed in human form in OOT. There is also the ruined temple of time, and what appears to be the ruins of castle town as well, similar to the design of that in OOT, suggesting this takes place after.