Given the amount of people still using 2012 Macs (including the Mac Pro 5,1, last generation of cMBP, and first generation of MacBook Pro with Retina Display), I definitely hope you're right. But Apple has done back-to-back hardware drops on iOS plenty of times in the interim, including iOS 11 which caused a lot of grief for users of discontinued 32-bit apps at the same time. And the massive Mojave unsupported Macs thread shows a lot of people are still using 2011/2010 Macs even today, yet Apple couldn't care less.
Of course, none of this speculation would be necessary if Apple were to give older Macs the proper decade of support they should get. But to Apple, caring about the environment is only worthwhile when profits aren't affected...