It turns out that Apple keeps a handy list of laptops you should definitely upgrade from if you're still using one of them.
Apple updated its official master list of "obsolete" products this week, as spotted by 9to5Mac. Particularly of note is the Mac section of the list, which is now home to six MacBook laptops that weren't there before. According to Apple, these six MacBooks are now obsolete:
13-inch MacBook Air, early 2015 13-inch MacBook Pro, 2016 13-inch MacBook Pro, 2016 15-inch MacBook Pro, 201613-inch Retina MacBook Pro, early 201612-inch Retina MacBook, early 2016
It seems an explanation is needed on what Apple considers an "obsolete" product and how it makes the list. Put simply, if Apple stopped selling a product over seven years ago, it's deemed obsolete. This means Apple will no longer provide repairs -- and third-party repair services can't order replacement parts either.
There's a separate "vintage" category for products that Apple stopped selling between five and seven years ago to indicate that repair parts might be limited, but are still possible.
Unfortunately, if your MacBook is on that list, it's definitely not possible (or at least not easy) to get a repair done at this point if it breaks. It may be time to upgrade.