Our current minimum iOS version is 11, but this has to change over time, and it's Apple or Microsoft who force the change on us - there's nothing we can do about it.
There's no imminent of your SkyDemon simply ceasing to function, but there's a good chance that over time your old software will stop understanding the new ways we're doing some things - such as new ways of transmitting aeronautical or scenery data - and some parts might not work so well. At that point, it really would be best to treat yourself to a brand new device which will hopefully give another ten years of service.
I believe that by the end of this year iOS 12 will be our minimum, but that might stretch into 2025 a little.