I think the story of the second game is pretty hard to drag out too long. The idea to end the first season with *that event* makes sense out of context, but it would mean an entire season of padding since it's not a mid plot event, it's what starts the plot.
I also think that they should use the show medium to instead cut between Ellie and Abby more than the game did, so I have a hard time seeing a good middle point of the story. I'd probably prefer one season being made from the second game and they can trim off some fat, and possibly have more than 9 episodes.
Well, wouldn't the middle point be the switch?