The kinds of hardware changes that Microsoft would make in response to knowing Sony's decisions would be the kind that can be made later in the process.

Imagine it's two years out from new console release and Microsoft gets their hands on Sony's specs. They look at them and realize that Sony's next-gen console is noticeably faster than the next-gen Xbox. Microsoft could shore up their hardware by requesting a larger GPU, more cache on the CPU, more system RAM, or higher clocks. Those aren't changes that can be made on a dime, but they are doable at that stage of development. Higher clocks in particular would be relatively easy: it means eating a higher defect rate and likely spending more on the power supply + cooling, but the silicon itself can be unchanged.

Alternatively, imagine this scenario in reverse: Microsoft learns that their next-gen Xbox is substantially faster than Sony's PS6. They could have their hardware parred back so as to lower manufacturing costs.

It would represent an enormous competitive advantage for Microsoft.