I don't think you can downplay the allure of the potential of a Championship. Larsson is in the part of his career where he is at the point where he either goes for it or he retires without one. He's not in a position where he can wait out a rebuild or wait for a core to age into their mid-20s.I don't think Larsson will ever play here again because of the very reason he left.
When Adam left, the Oilers were still in a rut. They weren't the deep roster they were today. And his job was primarily the guy that made sure the team didn't singlehandedly lose hockey games when their scoring lines weren't on the ice.
His Dad's passing was tragic, but time frequently heals those wounds. And Adam is still a very popular person in that locker room and in the community.
I think it would make a lot of sense for him to consider a run as an impending UFA and if he fits in the same manner as Ekholm did, it would really be strange for him to overlook the potential success story should he stay through the team's full competitive window.