Yeah, this series is not over. If Cleveland finds a way to make it 2-2, it's a whole new series.
That said, if Boston ends up winning Game 3, I honestly wouldn't be surprised if they got the sweep. I do agree that Cleveland isn't as hostile an environment as say, Milwaukee or Golden State or OKC, etc. But I do imagine that the crowd will be energetic early and CLE will come out roaring in Game 3.
The key, like in Game 2, is for the C's to weather their runs and stay in it. Don't fall behind by 15+ early. That was key in Game 2. Despite Lebron going off and Boston having some cold stretches, I think the largest lead CLE got was just 11, so we stayed within striking distance.