Mark Cuban was a test - whether Donald Trump could let one little thing slide without blowing up. He failed.
No, she failed. Trump's faced tougher opponents than Hillary. He's bluffing and trying to get her to focus in on what he did in the primary debates, which is exactly the type of stuff he won't do on Monday.
Let's just agree to disagree with that (but that Republican field was a god damn clown car of incompetence who would've crashed and burned in the general even harder than Trump or would've had no chance of making it out of the primary anyway).
We really have no idea what he's going to do on Monday's debate, which will make it worth watching. So far his people seem to be saying they're having trouble getting him to have a more conventional debate performance, but perhaps they aired that to lower expectations, which would be very clever of them (and Conway, like her or not, has a few of those up her sleeve).