I also think there won't be any half breeds diluting the gene pool. I can't imagine it would be allowed.
Ooh! Good point! The leaders of "New Vulcan" may forbid Spock to "donate" genetic material since many of that species see him as "less" than Vulcan. And given their limited numbers at the moment, I suspect they will want only the "best" genes to be replicated.
Ironically, this might give Spock and Uhura's relationship a better chance to develop.