I'm sorry but that isn't possible. Trump has said recently that his plan is going to require coverage of preexisting conditions. As soon as you dictate that you have to require people "buy" insurance, hence the mandate. No one in their right mind would buy insurance when they have to take you later if something goes wrong. So it isn't going back to what it was period if Trump does what he's says he's going to do. And if you have to take people with preexisting conditions you no longer are talking about "insurance". The risk element is gone. It would be like requiring home owners insurance companies to cover preexisting conditions... Then you can buy insurance after your house burns down...
Your sentiments are valid although they are premature. First, we don't yet know what Trump's plan will look like. Second, Trump is the consummate business man. Nobody would know better than he what you have just explained. Trump is not a fool. He knows that forcing companies to cover a situation after the fact is insanity.
1. We don't yet know the specifics of what Trump will propose.
2. We can't know how the proposal will be modified by Congress before it is passed.
3. No matter what Trump does, it has to be better than Obamacare.
We are so used to being screwed over by politicians that it will take time to get used to the idea that just possibly we have a real competent guy, who knows what he is doing, and who is on our side. At this point, that is still difficult to comprehend.