Begich is the likely candidate but it would be great to see Forrest Dunbar make an attempt, especially since he was one of the masterminds behind the operation that created the "independent with the support of the Democratic party" model that has been so successful.
Begich is the reason we are in this mess. If he didn't run Walker would most likely have won. It was only out of bubris he handed the election to Republicans
Wasn't Walker's polling against Dunleavy worse? AK-GOV has a bit of a curse for incumbents seeking reelection, and Walker's term had not been crisis-free.
Edit: your argument would still make sense despite this if you believe Walker's campaign was crippled by having to expend resources fighting off Begich.