Any vendor is going to reach a point where they no longer are willing to support older devices. So you have three choices:

1. Run with the vulnerability. This is incredibly stupid and I’d hope no one did this.
2. Replace the OS on any such device with something open source. Probably the best option for those who already own such a device.
3. Never buy a proprietary device in the first place. Unless you really, really need something the propriety device offers, a beige box running some flavor of 'nix is probably a better long term solution.

Ok, I guess there is a fourth option. Learn to enjoy that vendor bending you over every few years. This is what many businesses do and it can make sense. You just need to have lots of money.