Microsoft have a goal that states they want to get to " 1 engineer, 1 month, 1 million lines of code. " You can't do that if you write the code yourself. That means they'll always be chasing the best model. Right now, that's Opus 4.5.
"Microsoft has over 100,000 software engineers working on software projects of all sizes."
So that would mean 100 000 000 000 (100 billion) lines of code per month. Frightening.