NFL.com has an article on the "Top 10 records never to be broken in NFL history". A few comments come to mind:
Derrick Thomas's seven sacks in one game doesn't seem that unbreakable given the fact that just last season, the Giants sacked Donovan McNabb 12 times, including 6 by Osi Umenyiora (just one less than the record).
The '72 Dolphins' "perfect season" doesn't seem that unbreakable either, given that (again, just last season) the Patriots were one defensive stop away from 19-0.
No mention of Jerry Rice? Take your pick on which of his records is the most "unbreakable". I'd be willing to bet that both the "7 sacks in one game" and the "perfect season" records will be tied or exceeded before even half of Rice's records are broken.
Of those listed, I think the ones most likely to be truely unbreakable are the longevity-related ones: Landry's 29 seasons with the Cowboys, Favre's 16-season consecutive starts, Shula's 347 wins.
