Well, the original question was What if they restrict running compilers? and not What if they remove compilers?.
Restriction might be a requirement of special licence.
This would effectively remove ability to execute arbitrary code from most of the users.
The ones who want to run arbitrary code or develop software will have to pay. If someone complains about this, they would be told to shut up and would be explained how this is actually a benefit for majority of the users.
Anyway, I will stop here.
Edit: I think that Apple is not doing it only because it is not their focus at the moment.
Apple is going actually in opposite way and you can see it with recent changes on iOS. To run apps on iPhone, you don't need to buy a developer licence for 100$ anymore. They support more extensions for apps. On last Apple keynote Microsoft was presenting Microsoft Office running on iPad Pro.
The special licence you are talking about actually exists. You can sign your Mac apps with a certificate and it will not ask a user if you want to open it, but this is not restrictive at all. This is actually a benefit because nobody can modify your app so if they would force this, I wouldn't mind. Most of apps that I use are signed anyway.
I hope it goes better (the future of liberty in computing seems very dim), but I would be not surprised if it goes to the opposite direction accompanied by big ovations.
Restriction might be a requirement of special licence.
This would effectively remove ability to execute arbitrary code from most of the users.
The ones who want to run arbitrary code or develop software will have to pay. If someone complains about this, they would be told to shut up and would be explained how this is actually a benefit for majority of the users.
Anyway, I will stop here.
Edit: I think that Apple is not doing it only because it is not their focus at the moment.