Thats officially supported. I have personally run stuff a year or two older than official support multiple times with 0 issues.

And 6 years is typically the lifecycle of any laptop. By that point most people start looking for a new one.

My 2011 mbp is doing very well with a new battery, ssd and some extra RAM. I will still receive security updates for years if I'm correct but no more mayor updates indeed.

Man I love my 2012 rMBP. I recently left it on a flight and was devastated. Got it back, luckily. Greatest laptop ever made. I'm taking that thing to the grave...