The only problem Leach had was lack of games, he's def our best bet. Second spinner is a problem but not one I can see causing an issue for ages, we won't play 2 in our summer and at the end of the year maybe Sydney we would need 2 but nothing else comes to mind.
Unless England see better value in making Mo Ali fill that role and not Leach, I expect Ali to just play one day cricket.
To be honest, he's batted everywhere in the order, scored some very very good runs from number 8 but has always been a difficult selection. He's said himself he is a batsman who bowls.