If he wants a different challenge (and let's face it, he's done everything he can do at Barcelona - it's like having this clean carpet which you clean every day, eventually you'll realise I've done everything I can for it) then there's a few clubs here who'd want him, Chelsea, Spurs (when Harry leaves) among others and I don't think he wants another job in Spain. But in truth I think he's taking a year's break at the end of this season because he's admitted to stress. Realistically Barca won't win the league this year but they'll probably win the Champions League, as well as the trophies he's already won this season and since 2008.
In 2008 he got rid of Deco, Guily, Edmilson, Ronaldinho, Ezquerro, Thuram (though he retired)and Zambrotta amongst others and promoted Busquets from Barca B and bought players like Dani Alves, Pique and of course started playing those young players and has been bringing them through ever since. If he went to Chelsea, the likes of Terry, Lampard and Drogba will be packing their bags.