Newcastle fans will have to adapt to life in the Championship next season
Alan Shearer, who as a short-term manager could not prevent the club from being relegated seven years ago, said relegation had been "coming for a while".
"When you've been flirting with relegation for so long the inevitable will happen," added the former England captain.
"When you don't address problems that have been glaringly obvious for years then, ultimately, you get what you deserve."
In response to managing director Lee Charnley's promise of a full inquest, Shearer said: "That's one thing Newcastle have been good at this season, putting statements out.
"Maybe they should have looked at what went wrong a bit earlier. It might be a bit late to look at it now."