I am new to linux mint and linux in general but I find that Ubuntu and Mint are easy to put onto "Grandma's Laptop", turning off auto-updates (yeah yeah I know) to minimize the interaction Grandma has with the computer itself and letting her go to town. Every so often I update her stuff but I keep it off so if there are any problems I can just correct them, and with Ubuntu I have had a lot of issues with "last edition" updating.
The "Linux Mint Refresh" build would be a packaged setup with a longer stable support with minimal changes with the idea of supporting older computers.
The UI should be 2D, lightweight and simple.
I'd like to see Spotify already in the build (I dont know about Mints closed-source policies, but it would be really nice to have Spotify already ready to go)
The Linux Mint Refresh project could have a list of laptops and desktops it is confirmed working with, Maybe always starting with machines at least 2 years old and beyond.
Having an option for "extremely lightweight" virtually entering into chromium territory with only a browser as the OS.