So basically moving to a system similar to Southwest -- no separate change fee, but you pay the fare difference (so the closer in you change, the more it costs). Definitely pros and cons of each, but seems like a good move with all the uncertainty that's likely to persist for a while.
I will be interested to see how far carriers need to go to woo back discretionary travel, i.e. what other promises/flexibility might be needed. A lot depends how many people were directly financially impacted or knew someone who was by trips that were cancelled but their hard-earned cash not returned -- from the failed attempts by United and Southwest to deny refunds (25 hours, UA? No refund for flights canceled "due to the government" WN?), or the more successful schemes some foreign carriers have employed. I'm still hesitant to put down actual cash for travel yet (miles okay), but we all will do so eventually, just at a lower level than before and with a lot more care and skepticism.