So this is one of the most debated things on here (right next to Starleaf/Brackenleaf), will future black foals have starfire? Here are some of the reasons why or why not they will have starfire:
The prophecy thingy was fulfilled by Star, so there's no need for another pegasus to receive starfire
All black foal should continue to receive starfire because that how always worked
Black will become a common color for pegasi, but only those sired by the hundred year star get starfire
No more black foals will be born, unless they are a direct descendent of either Star or Nightwing
I asked Jennifer if Riversun has the Starfire and on Twitter she confirmed that she does. Jennifer wants to write a story about Riversun and her Starfire. But she hasn't gotten the opportunity.