We really shouldn't be comparing Pogba to Zidane.
Those were different times and Zidane was already one of the best players in the world, while Pogba still has things to prove.
Obviously I'd like Paul to stay, provided we can get a better (more reliable) CM than Khedira and a world-class AM, he'll become unstoppable. Replacing him will be a much harder task than replacing Vidal.