Before Heather and Laura the last girl to win a junior grand slam was Annabel Croft in 1984 (Australian and Wimbledon). Heather's reward includes a WC to next year's US Open Women's Qualifying event and (almost certainly) 3 challenger direct entries for finishing the year in the top 10. Heather may be encouraged to enter the Eddie Herr and/or Orange Bowl in order to improve her chances of a top 5 finish (or top 2 even if Noppawan doesn't win her third doubles grand slam - giving her a big bonus), which wins entry into higher-grade challengers.
Heather may be encouraged to enter the Eddie Herr and/or Orange Bowl in order to improve her chances of a top 5 finish. I'd be amazed if she didn't play the Eddie Herr, given it's held at Bollettieri's where she trains, and probably the Orange Bowl too.