I think there was a perfect storm there when Moyes went. There was not one reason why it failed like it did. Anything other than a title win would be seen as a step backwards and a failure. That pressure, the lack of respect (if we believe the stories) for him from the leaders of the group. I am not sure that set of players would have taken to Martinez any more. In my opinion the only way there could have been a true continuation is if there was a truly great manager, like the ones mentioned took over.
Even then, it would still have been a difficult task to take over from somebody who was the club, from top to bottom. Like Wenger as well, to be at a club that long, any manager coming in would have struggled to an extent.
I do agree that in an easier situation it might still have been a step too far for Moyes, I have always said he has a ceiling. I will definitely except that ceiling now, as this time around it is not a long term appointment. Short term burst with an eye for a continuation plan.