There's no way Fury will underestimate Joshua. It's the biggest fight of his career and if he didn't underestimate Whyte and managed to motivate himself for that one, there's no question at all that he'll respect Joshua and be well up for this one. I don't think anybody has called his bluff, he's clearly wanted this fight for a long time but wasn't willing to be a lapdog and treated like shit in previous negotiations.
Can't write Joshua off at all. Think Fury wins but you never say never in boxing.
I'm not sure I'd say Joshua has nothing to lose either, lose this fight and I don't really see a way back for him tbh and there's big question marks over Joshua mentally.
That all said, I'm still not believing this fight happens until I see them in the ring