There would be Greco-Persian culture instead of Greco-Roman though.

would probably be the same

 

there's no way his conquests wouldn't break up on succession, simply too expansive

historically 1 month travel time was already stretching it on stability

Why wouldnt he try to conquer Gaul?

ancient germanics were too tall

The Empire is not 1 man, the Empire is a self-reproducing system of governance and control, that can function without a single person in charge, it can replace it

 

American Empire for example has the line of succession

https://en.wikipedia.org/wiki/United_States_presidential_line_of_succession

 

and even bizarre things like this

https://en.wikipedia.org/wiki/Designated_survivor

 

just to insure that system persists

 

Ancient countries also were very silly, didn't think such things through. everything revolved aroudn blood and relatives, making it all vulnerable to personal issues and qualities of people who were not fit for " a job" of rulling an Empire or were raised by people from other Empire and had conflicting loyalty