Nah, as Steve said, mobile network operators are dumb pipes, basically utilities. Buying a cellular provider would be like Apple buying the garbage or water company.
There is no value add from mobile network operators. That's one reason why Apple doesn't allow carrier partners to preload their own skankware and there is no carrier branding on iPhone/iPad hardware.
Plus, Apple does not acquire companies that only benefit one market. Buying an American cellular company doesn't help iPhone users in China, United Kingdom, and Korea.
Worse, telephone companies aren't very profitable compared to Apple. Apple's profit margin is about 22%. AT&T's profit margin is about 6%. Verizon's profit margin is 2%.
Acquiring a telephone company would devalue Apple and most likely shareholders would revolt.
Steve Jobs said a lot of things... Doesn't mean it was the truth, then or now. He was a master at deflection.
I think you may be off quite a bit on margins for most everyone you've listed. Would be interested in your source.
Also, as mentioned, there are a lot of assets with these two companies, especially spectrum. AT&T wanted T-Mobile for theirs. Sprint has a lot that it acquired from Clear. There's also the IP. Don't ignore the value all of those assets might provide.
There would be little to no effect on other carriers or countries. Apple would still produce models that worked everywhere else, they would simply be able to leverage their own infrastructure and possibly even offer something other than "dumb pipes." There would also be nothing preventing them from acquiring carriers overseas as well.
It seems to me, if I remember right, that at one time Apple had planned on offering the iPhone as an VOIP only device on a network they controlled. Obviously that's not the route they went, but having their own cellular service wouldn't be such a far fetched scenario in that context.
Think of it as the same complete end to end service model they already provide with it's current eco-system. Man, what a lock in that would be, but if it promised better quality service all around, I would be game.
Cheers!
---RASTER