Players break metatarsals all the time. It is a good time to get the injury(if there is any good time.
He should be back, rested after having the summer off, ready to start preseason in July.
A third injury in a row will possibly make clubs think twice about trying to sign him and yes I do believe there could be interest in signing him. He was hugely impressive before his leg break and he does still have Baines ahead of him for probably his best position.
A fit Oviedo would be a huge boost to our squad next season.