"Sustainable salaries" won't fix this issue, as real estate is a competitive market. If you double the salaries of everyone who works in Manhattan, you will still have the same number of people living near work, just paying more rent. A salary increase only helps you move closer to work if other people don't get an increase and you can price them out.
In the end, there are only three options: build more housing where people want to work and live (but it has to be high-rises, not houses with backyards), better remote work options, or better transport infrastructure.
I'm saying employers contribute to the poor salary/rent ratio in cities, especially when we factor in commute times. They should acknowledge the problem and help solve it as a strategic priority.
Working towards your list of ideas is a viable approach. Having core butts-in-seats hours that coincide with rush hour and not paying people enough to keep the commute down is not.
In the end, there are only three options: build more housing where people want to work and live (but it has to be high-rises, not houses with backyards), better remote work options, or better transport infrastructure.