Unless there's a radical change in the voting or the voting members like Polian, it is not a cinch that Belichick gets in next year.
I've been on enough committees to know that when there's blowback, the people voting one way do not revise their position, but instead they become ever more entrenched.
If Spygate is a reason for not voting him in, and even if you only wanted a one year punishment, all this blowback -- forcing people to defend their Spygate rationale -- ingrains it in the voter as purely logical and reasonable position. So, you might have gone in NOT voting for Belhcick THIS YEAR, but when you were exposed and had to defend yourself, you begin to see Spygate the way Baseball HOF voters see steroids.