Based on the last few times I’ve seen him I don’t think it’s going to be factor much longer to be honest. Whatever happens with his wife, I think he’s about to retire from public life due to health (or lack of).
In their particular situation I would be fine with “President and former President Clinton”. In general I think “the President’s husband” since it really is not a official position anymore than first lady.
Has it come up with any other country where they have a similar position to First Lady and a married woman was elected leader?
I think officially he might be referred to as the First Gentleman, but practically speaking, the media will probably avoid using that term as its clunky and sounds odd. They’ll probably refer to him in stories and articles as the former president Clinton or just Mr. Clinton
Less irony than addressing letters to Denny Hastert in prison as “The Honorable Mr. Hastert.” Its the sort of irony you can savor. Clinton won’t be the first or last for title irony.