I don't think anybody knows whether there is a real difference, but the increased strictness of GPL3 such as its anti-TIVOization (https://en.m.wikipedia.org/wiki/Tivoization) clauses certainly make a lot of lawyers concerned.

Where exactly the border lies between and not linking is a grey area, legally, that hasn't become clearer with GPL3.

It wouldn't surprise me to see bash go from the standard install, too. Apple is slowly removing all GPL code from its OS.

I hope they make ZSH the standard shell. It's similar enough to bash to not disrupt most workflows and Apple has been able to update it due to its permissive license.

I use ZSH as my main shell on OS X. I find it superior to bash in almost every way (especially with oh-my-zsh) except in ubiquity. Even so, I have no problem using bash if that's all that's available, the two shells are fairly compatible.

It was the primary shell in 10.2 or 10.3 after tcsh or csh (its been a while I can't remember well).

if someone uses your software in a way that is honoring the GPLv3, but you don't like, you lose any ability to sue or further restrict them. Even though the ghost of Steve Jobs (Forstall) is no longer haunting the building, Apple learned the lesson of "sue early, sue often", and Stallman/Moglen sort of got in the way of that with GPLv3.

Tivoization was another issue, especially with Apple's tendency to lock down their platform.