All these would be not be usable because they are not sandboxed. Basically I would have to install Windows on my Macbook and I would virtualize Mac OS X so I can use Xcode and I would use Windows for everything else.
It would be suicide for Mac OS X and if you think Apple is so stupid to do it, okay then...
A: Business Insider is rarely a source of truth, at least when it comes to anything Apple. "Click bait" seems to be their sole goal in life.
B: Apple never precluded Google from putting their own Maps app into the store, they simply replaced the preinstalled version with their own when (if memory serves) Google both demanded too much user information and declined to offer vector-based maps
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.
I.e. not programmers but users of software from big software companies.
and if everything was sandboxed you couldn't do it anymore.
Yes, you could not run arbitrary programs and Apple may see it as a feature.
You seem to be in big denial as it would be horrible thing to happen. I still see this as very likely possibility.