Hi all,
I just released an addon for Blender 2.8x that can help you optimize subdivision surface models and transfer materials to the low poly version.
There is no need for retopology or cage baking.
I made a demonstration video:
You can it on gumroad (paid, $29.95) : https://gumroad.com/l/VDqOR
Let me know what do you think 
Thank you.