IGN did an interview with JD Payne and Patrick McCay where they revealed a bit of new information. First of all is that we'll being a third version of Sauron along with his human and elf forms, a creature form which Payne called "puddle blob Sauron", which we actually saw in the first trailer.
They also admitted that they aren't really going out of their way to hide who The Stranger is, and that they are just trying to have the fans follow him on his journey of self discovery. They also said that we will be learning his name this season. So it sounds to me like he is going to be Gandalf.
I'll be honest, making the Stranger Gandalf is the one lore breaking thing that does bug me. If he's Gandalf then they've gone out of there way to do literally everything the opposite of canon. In the lore (just to use a few examples):
1. Gandalf didn't show up in Middle earth until the Third Age, and when he did it was on a boat, he could speak and was dressed, and
he was the last Wizard to arrive.
2. Gandalf
never went into what would be considered "The East" in Middle earth, he actually calls that out as the only direction he didn't explore.
3. He was given Narya, the Elfish ring of fire, from Cirdan as soon as he arrived in Middle earth, which was thousands of years after the ring was forged.
I think what really bugs me about this over the other stuff is that they had no need to do this, none of these are changes for rights issues or to compress the timeline to make the story of the second age fit. Its also just lazy. Having The Stranger be a Blue Wizard makes way more sense, and even making him Saruman would be interesting, Saruman wasn't evil when he first came to Middle Earth so he could easily fit in the role. I guess the second that they randomly added pointless Hobbits to the story they were pretty much telegraphing who The stranger was.
To be clear I'm still excited for Season 2 and I think I'll enjoy it at least as much as season 1, but like season 1 the stuff with The Stranger is almost certainly going to remain my least favorite part.