We’re not sure about the number of Android Auto users but Samsung will stop supporting Car Mode app. It can still be used but support won’t be provided anywhere. No updates will be provided by Samsung for the Car Mode.
Car Mode allows for an optimized driving experience. Even without an Android Auto device or device, you can just take advantage of the Car Mode. You may not be able to download and install it in the future though.
Car Mode’s last version is 11.0.20. A next build should not be expected because Samsung is dropping it. You are free to check out other new alternatives so you can use some of the more common apps like Google Maps and Waze.