If we can blow out Colorado we have a chance at getting ranked, if not then it we would have to be ranked at 4-0 if we beat Michigan (There are always top 25 teams that lose in their first 4 games).
Maybe week 1 Maryland vs23 Texas, did it last year on the road.
Week 3 Syracuse might play FS well at home.
San jose could be a trap for Oregon, they just do that once in a while.
Texas another chance to drop to USC on the road
TCU vs OSU, though not likely to drop from top 25 unless they loose week 2 to SMU, though unlikely in Texas.
Also as mentioned this is what makes the Colorado game all the much bigger, good showing vs them and a couple teams dropping would likely get Huskers into the 22-25th spot. Beat unbeaten UM, easy mid teens, win vs beaten UM with Huskers 4-0 around 17-20 in the ranks.