Matthew Panzarino:

The point is that the FBI is asking Apple to crack its own safe, it doesn’t matter how good the locks are if you modify them to be weak after installing them. And once the precedent is set then the opportunity is there for similar requests to be made of all billion or so active iOS devices. Hence the importance of this fight for Apple.

That is exactly right. All devices, even newer ones, will be susceptible if the government is successful.