At the beginning of the month, Apple officially stopped supporting the device, which was released in mid-2012. (To the report)
This means that users can no longer get repairs from Apple or authorized service providers. In the event of a problem, they must resort to independent service providers.
Now the turnaround. The step is rather unusual for Apple, but the company has granted the device with the first Retina display a reprieve and announced that the vintage status will not take effect until December 31, 2018. This means that hardware support and the supply of spare parts will continue. So if you still want to have something replaced, you can go to an authorized service provider or Apple. This series of MacBooks has Metal graphics chip support, which is why macOS 10.14 Mojave can still be installed on it, which is known to only run on devices with Metal compatibility. Perhaps this explains Apple's unusual step.
With a few exceptions, Apple's rule of thumb is to produce spare parts for devices for five years. Only then is the customer forced to look elsewhere for spare parts.