Same with C++, new standards will support old code. But they'll disagree on using the new features in the new toolchains. Or more likely, they'll just use the new features. So there's no option of sticking to old feature sets, you will encounter the new ones at the very least.

Even with a style guide in C++... Google is known for having one. I was forced to change how I use basic strings multiple times there. They also changed the rules around refs (&).