The other thing is defenses like Eagles and Jaguars lost a lot of turnover creation this summer. Eagles lost a lot of defenders (because $$$) and have mass injuries in their secondary.
What I love about the Bears' defense is it is not gimmicky and it does not rely on turnover creation. They force a lot of turnovers, sure, but those are a product of a pass rush that does not need to blitz to get sacks.
But I do agree on one point: defenses get expensive and are very difficult to maintain long-term. When Roquan Smith, Leonard Floyd, Kyle Fuller, Eddie Jackson, and Amos Jr. all become due for contracts, on top of what they're paying Khalil Mack, the Bears will need to make tough decisions. Hopefully Mack will be elite for many years to come, but if not, their window may be shorter than three years.
My gut, though, is that Mack stays elite for a long time and they build around him and Smith. Everyone else around them will rotate.