What happens when I turn off SSO in jira cloud?

[Jeremey Sansom]

So we are migrating email, and currently have SSO and we are changing IdP and email.  My question is, what happens if I turn off SSO in Jira cloud?  Will it prompt users to enter a new password, or will they still be able to use the same password with SSO off?  Users will still have access to the email via email forward from old to new, but the passwords for old accounts will be changed.  

I've read it reverts back to their Atlassian account password, most of the users have only ever signed on using SSO.