I think Inter will play a decent game at Barcelona stadium but I think they will not be able to get a draw there so probably they will come out of there with 0 points.This will make it very difficult for Inter to pass the group stages of the Champions League,they need at least one point in this game in order to hope for qualification.
As things stand now, with Barcelona's really poor form and Messi being injured, I see no reason why inter who are in one of their best forms in a very long while, can't go out there and get all three points, I ain't saying they will, but they are in a good shape and can defeat Barcelona.
I also think it's too early to start talking about qualification chances, note that Barcelona also didn't win their first game against Dortmund, so everything is still open, I believe Barca and inter would qualify at the end of the day.