Microsoft is ending support long after app developers did. The ‘app gap’ between the platform and the burgeoning iOS and Android market was what did it initially for Windows Phone’s waning popularity circa 2015.
If you still have a late-era Windows Phone it doesn’t mean it’ll stop working, but it’ll never again receive a software or security update. Much like the select few people clinging onto an old school BlackBerry, your device will work, but you probably shouldn’t be using it.
Back end services will continue to run, such as email, but even these will be phased out – and when you can’t rely on your phone to do even the simplest tasks, it’s time to let go and upgrade. Most of you have, to be fair.
Microsoft Office apps will stop working on Windows Phone in January 2021, so if you are a die hard fan you might be able to eke out another year (!) from your handset. But we wouldn’t recommend it when there are so many good, affordable Android smartphones on the market.