It's already possible, any physical lock or home or safe can be opened with a warrant. The fact that we're almost at a point where we can hide something from the government (even with a warrant) is groundbreaking.
It's perfectly fine that the FBI or the police can open a physical lock with a warrant. The warrant is supposed to be delivered by someone representing the Justice department, which is (theoretically) independent from the police. What would be unacceptable is that they could just bypass that authority and enter to anybody's home on a whim.
Which is what they are trying to achieve when they asked Apple to put a backdoor in their Iphones.
"The warrant is supposed to be delivered by someone representing the Justice department, which is (theoretically) independent from the police."
I hate to break it to you, but the FBI is part of the Department of Justice. I think you mean that a warrant needs to be issued by the judiciary, which (as far as I know) is a truism. Courts issue warrants, there is a warrant in the Apple case, and it in no way involves a "backdoor" being placed in all Apple phones.
You really might want to look up some of the facts about this case. It's not nearly as general as you think it is.
Warrants are really only a defence against mass, dragnet style surveillance since with enough will, anybody can become subject of a warrant if those who are investigating them have enough will to get one.
