Observations thus far.
So here's the thing,
It's pretty much obvious that Clementine encountered Christa & Omid at the end of season 1, the screenshot generally speaks for itself. (For those who argue otherwise, there would be no time for Telltale to interweave a story on Clementine meeting two OTHER figures, given the probability on the subject, I saw it's confirmed.)
The next thing we notice is that Clementine and Omid next to Gil's Pit Stop, a major location for the 400 Days survivors. But what catches my eye, is the time placement.
We know Clementine will eventually be alone in the next episode, from other screenshots previously released. So, with that being said, where is Omid (or Christa possibly)? My purposed answer:
They will die. Clementine looks the same age she was in Season 1, because of her pig tails and her size. It is noticeable that Clementine grows taller from the trailer, meaning that the first season will possibly span throughout many months using flashbacks, at least this is what I reckon. Maybe Omid is killed by Shell's group, and fed to the watchdogs? Maybe they are seperated, and Clem never finds him? Only time will tell.
The second thing is to clear up discussion to who Clementine is sitting with at the table: It is Nate. Yes, from the back it looks much like Kenny, however, do not forget Kenny and Nate share similar hair styles, as well as the fact time has probably passed since we last saw Nate. Nate was a very hard character to trust in 400 Days, and my guess is that it is him in the picture, in regards to Clementines facial expression. (Also, we know Clementine stumbles upon a house in the middle of the woods, so it's even more likely because Nate was around Foresty-areas, while Kenny was not.)
TL;DR (From my observations)
Omid (and possibly Chirsta) are here, but not for long.
Clementine is seperated and meets Nate in a house in the woods,
It will take place over a course of many weeks, possibly months.
400 Days connection is referenced, but maybe not so important after all.
Comments
I'd say a lot of what you are saying is true or makes sense but Clem is at least a year older and bet 400 Days will have a bigger impact than a refrence, maybe not so much in episode 1 but over the course of the season.