Koeman maybe in the running but our bookmakers have Sevilla's Sampaoli as the clear early favourite though
Sampaoli 3/1 (Paddy Power)
Koeman 7/1 (Skybet)
Valverde 12/1 (Skybet)
Tuchel, Pochettino 14/1 (betVictor)
Jemez, Unzue 16/1 (Paddy Power/betVictor)
I would have thought Koeman unlikely but he's still very well thought of at Barca from his playing days, and they have a history of appointing former players like Cruyff, Pep and Enrique
Guillem Balague thinks Sampaoli and Valverde are particular favourites although Pochettino is rated very highly too with only his past history as captain of arch rivals Espanyol being a big deterrent to any likely appointment
http://www.skysports.com/share/10771943