Yeah future Zorro  is going to be a hard sell no matter who is attached, especially when even casual "fan" reaction tends to be hesitant(that includes me)  to negative ... "Zorro belongs only in the past!" or "Only the Banders version counts, anything else is automatically crap! attitude. 
And these are "fans?"
Yet  they'll gobble up   million reinventions/modernizations of Batman without much  thought, they automatically draw some arbitrary line Zorro  has to stick to the past.  Even though as pointed out;  he was doing the whole modern/legacy thing before Batman even existed.
It's  faithful  to the character, there is    legitimate and  strong foundation for a future/legacy Zorro   in the history of the  character. 
The production team just has to ride-out and ignore the negative/ignorant crap, if they have a vision just   go with their gut and stick with it. 
If Bernal is indeed still attached,  and now Jonás Cuarón the connection and the circles they move in; (which indirectly include  Alfonso Cuarón,    Iñárritu, Emmanuel Lubezki (Chivo) and  Guillermo del Toro is friends with this group), these are some of the more creative and celebrated  filmmakers out there right now, so if by  way of Bernal and Jonas Cuarón it sways under their influence,  there is   potential for something exceptional here. 
It gives 
me hope anyway. 
The group;
Guillermo del Toro, Alejandro G. Iñárritu, Emmanuel (El Chivo) Lubezki, Alfonso Cuarón,  Jonás Cuarón
What would be incredible is if they could get (the father) Alfonso Cuarón to direct the classic version, the origin film. And (son) Jonás Cuarón to direct the modern/future   legacy version. ... And then Chivo as cinematographer on  both!  

t: