I still think the Sixers have too much youth and depth not to come out on top in this division, after the start they had. If the Celtics had the easier part of their schedule in this second half while the Sixers had their most difficult, I might feel differently. But since both teams have it really rough from here on, I think the Sixers will have the edge.
It will probably come down to the 4 games between the teams; if the Celtics win all 4 of those games, I think they have a great shot at winning the division. But I think it's more likely that the Sixers at least split those 4 games.
In terms of seeding, the Celtics should just focus on getting that 6th seed so they can avoid a first round embarrassment.