I'll be surprised if they "don't do jack" after graduating from Harvard, oh wait you are referring to running. . .
In my opinion they have more freedom to do whatever they want after college than a grad from Oregon, CU, Wisco, etc.
There are plenty of post collegiate running options in Boston ranging from recreational clubs to sub-elite/elite groups (depending on your definition). Any of these will allow them to enjoy the sport in the future, which is important for anyone who loves running.
Outside of running the Northeast is ripe with many non-running opportunities. These aren't exclusive to new england and the northeast but they are very plentiful here.
Lastly, the running scene is great in Boston with so many different types of people enjoying the sport. The racing options include the club xc, indoor and outdoor track season, BAA and NYC marathons, hundreds of races that take place on the roads and all other types of terrain.
I think their futures are well take care of and that is exactly what they had in mind with they chose Harvard.