Smart advice on future-proofing and backward-compatibility:
There isn’t a single, specific device, browser, and person we cater to when creating a web experience. Websites and web apps need to adapt to a near-infinite combination of these circumstances to be effective. This adaptability is a large part of what makes the web such a successful medium.
Consider doing the hard work to make it easy and never remove feature queries and @supports statements. This creates a robust approach that can gracefully adapt to the past, as well as the future.