Philly and NY Rangers are most likely if you believe that they want minimal disruption to what is already scheduled.
Games already scheduled against Atlantic
New Jersey: 1 (1 home, 0 away)
NY Islanders: 3 (2 home, 1 away)
NY Rangers: 5 (2 home, 3 away)
Philadelphia: 5 (3 home, 2 away)
The Philadelphia thing is a little interesting, considering there is talk of adding another game against them in Philly on January 19th. I guess if thats true, and if this format is true, they'd have to swap opponents on one of the other games. The adding of that game made a lot more sense back when i thought they'd have 7 games against division foes, not 4/5 games.