Could Unity help provide Virtual environments that allow Unity games to be compiled into the future?

Unity moves forward every update and what used to be buildable needs updates but what about legacy Unity games, 5,10 ,20, 40, 80 years from now. When their developers have moved on the the next level but left behind legacy source code. Will we still be able to build those games or will we need emulation to build legacy Unity games?

Could Unity help provide Virtual environments that allow Unity games to be compiled into the future?

Original idea from John Carmack on Twitter: "I strongly encourage all game developers to take steps to archive their development environment so you are confident you can rebuild things years in the future, which does not automatically happen!" / Twitter