Do you think Villa are going to stick by him even if there is a threat of relegation? I personally feel there's a tentative understanding in what they've done with the contract. As long as he keeps them above water, it'll prove prudent, but if there is a genuine chance they will drop through the trapdoor back into the Championship, they won't hesitate to sack him.
If we evaluate a managerial pay off vis-à-vis the financial calamity of going back into the Championship, even with the parachute payments, I think it's a no-brainer, although having said all that, I do think he's the safest of all because they really don't want to get rid and will only do so if they must, whereas I think a few of these clubs have managers whom they believe should be doing much better with the resources at their disposal and are thus upgradeable.