1. "Born on a Monday..."
I shouldn't really have to address this one because it's obviously Solomon Grundy, or at least Arrowverse version of him.
2. Someone else survived the island.
My first thought is Slade(hopefully have taken the name Deathstroke by then) but Shado was also on the island, and it's uncertain, after the episode "The Scientist" that Slade will even make it. My money is still on Slade because I believe the serum he took is what will give him his abilities he has in the comics.
3. Amanda makes an offer.
My only thought on this one is Suicide Squad.
4. A better use for that clocktower.
Two main thoughts come to my mind on this one. Birds of Prey is my main one, my second being an Arrowverse Justice League, using the tower as the Watch Tower.
5. What is the question you should have asked?
Two thoughts on this one as well. The Question is my main thought, but I also look at the teaser as a riddle(as if they all weren't), meaning I also think it may be The Riddler.
6. Ollie is not the first vigilante.
Now I firmly believe that Batman will never make an appearance in Arrowverse, but I don't think they will be shy about using members of the Bat family. So my first thought is Nightwing/Robin. When I look back at the first season, they made references to both Central city and Bludhaven. Who is the first hero or villain that comes to your mind when you think of these cities? Central city: The Flash. Bludhaven: Nightwing. The teasers in the first season of Arrow could be setting up these heroes, since we know The Flash will be debuting soon(which we already have Barry Allen).
7. Not all hoods are green.
This one have people split. Half thinks it's Roy Harper as Speedy/Red Arrow/Arsenal, the other half thinks it's Red Hood. I believe it could be either one, but I'm putting my money on Red Hood. Reason being, is that for one, if Roy ever becomes a vigilante, we do not know he will actually wear a hood. Another reason is that they could have chosen to say "Not all arrows are green." or "Not all vigilantes wear green" but they specifically said hoods. It could be a good reason to bring Nightwing in as well.
8. A blank expression.
This is one of those that I do not believe is for a specific character debuting, but a specific scene taking place. I believe it will be the scene where Thea learns that she is the child of Malcolm Merlyn.
9. "Archer"
I believe this could be one of three things. The debut of Roy as a vigilante, Oliver realizing Malcolm survived, or a secret twist, bringing Tommy back as The Dark Archer.
10. "Rise"
This is the second one that I believe is referring to a particular scene rather than a character. Whoever is going to be the actual "big bad" of the season, I feel will severely hurt Oliver, and I believe "Rise" is referring to the scene where he overcomes his the suffering the big bad dealt him.
I don't know if I'm right, but I would like to know what you think. Do you agree with me(or at least for the most part) or do you think I'm way off. I would like to hear your speculations below.