It has been bemoaned on this very site. It's been a staple of the Northwestern football program for years, even a selling point. The commenters of this site have discussed it ad naueseam. This article won't be the last you hear of it.
No, Northwestern fans, you don't need to sound the alarms or go out partying in the streets. This isn't really what you wanted, I'm guessing.
But, in the year 2018, the streak is over. For the first time in eight seasons, Northwestern's coaching staff will feature some changes next fall.
Do not fear, coaching continuity isn't gone.