If Apple pulls out, then maybe. If Samsung pulled all it's Android phones, some other company would just swoop in and replace them. You would end up with a marked filled with companies with no morals, who just do what ever the government asks, no questions asked.
You run the risk of companies that are actually trying to do the right thing going out of business, and you left with the ones with no morals. Apple might be a bit different, customers would complain bitterly if iPhones where no longer available in the UK.
Nobody else has proven to be at his level, as far as I can remember. Not during my lifetime anyways.
Plus, the government relies on encryption for communication too. Are they going to say that only certain government officials should be allowed to use secure devices? What happens when someone in government wants to have a private conversation with someone in the private sector? The private sector person will need a secure device too, and we're back where we started.
The fact is our government needs to figure out how to keep us safe without relying on backdoors.