So how do we sync our mail now?

I think you and misunderstanding the article. It is only the syncing of mail settings that will not be available on iCloud. The iCloud email account will sync between other devices using the same iCloud account.

What is affected is the setting up of new non-iCloud accounts on any device. With MobileMe the setup could be done automatically by the Mobile me sync, from now on with iCloud you will have to set up these accounts manually yourself.