Why would they shut down the servers if people are still using their products?

Well my main modem router is easily ten years old and I'm still using it.

It's only a general question...cloud-enabled management of home devices is kind of 'newish' in the market and perhaps they won't support the back-end forever, so I'm curious as to how my hardware will work when I can't log into through the app anymore. This curiosity isn't limited to only TP-Link, it's a question surrounding all IoT devices:

https://www.google.com.au/search?q=what+happens+to+iot+devices+when+server+is+shut+down