Well, if Steemit.com has been saving their password for them they will need to now manually enter it (or copy/paste) into the steemitwallet.com site and then when the browser asks them if they want the browser to save it, they can do so.
They don’t need to reset their passwords, they just need their master to reveal their keys if they don’t have their posting (or other key) handy.
If you are saying there is a large majority of people who do not have their passwords saved ANYWHERE and have soley been depending on their browser to save them... well there are so many issues with that. This can’t be the way people save their keys, it just can’t.
I assume what has happened is people have gotten used to the browser saving them and now it’s not convenient because they have to go figure out where they saved them. I get it’s annoying, but they will need to go dig their keys out and enter it into the new domain.
This will probably be a good lesson for all users on key safety and I do hope everyone watches the video linked above about private keys safety.