United is farthest ahead preparing for the worst as a business. They are cutting capital spending, slashing flying, and eliminating discretionary expenses. They have raised additional cash and assume that their revenue is down 70% in April and May and not fully recovering this year. We don’t know yet if things will be even worse than this, and more drastic measures will need to be taken.
For now there aren’t any layoffs, but United is trying to reduce personnel spending and they’ve imposed a hiring freeze so that retirements will reduce their head count. Here’s the detail of the United Airlines voluntary leave plan.