A previous post on the board (since deleted) got me thinking about the safety of Michigan's status as the all-time winningest team. Michigan has that title by either metric: by overall wins and by winning percentage.
We recently took the winning percentage title from ND (I think somewhere around 2003 if memory serves), but have had the all-time wins for as long as I've ever been aware (and probably as long as I've been alive since I'm in my 20s).
I thought I'd see what it would take to lose the records. The all-time wins is easiest: we have 50 more wins than Texas, who's in second place. If we never won again, and Texas won every single game, it'd still take over 3.33 seasons for Texas to surpass us, assuming they play a 12 game regular season, a conference championship game, and even with a plus-one playoff system
The percentage record is not nearly as durable, not surprisingly. If we lose the first seven games and ND wins their first seven, they would have earned back the record. It'd take a fair amount more before Oklahoma could catch up to us: we'd need to lose 23 straight games and they'd need to win 23 straight games for their percentage to pass us (Texas has a higher percentage currently but has also played more games so Oklahoma's percentage catches up more quickly).
It was pointed out in comments that Boise State has a more malleable win percentage having played so few games, so I ran those numbers as well: they can actually catch up in 13 games (again, we lose that many and they win that many).
(Updated to more accurate calculations--the originals were slightly off; the change actually increases the number of games needed to catch up)