I would say not very much, medhelp.com and the others have been around for years and have that sewn up pretty much with far superior names that a newcomer will find it very hard to come along, though not impossible.
Would it be worth someone buying the domain to put in the time necessary?
I am not so sure, coupled with the fact that a domain like this can pretty much only go to a doctor without problems arising...you may be a ble to offload it for low $xx but I wouldn't hold your breath.
By the way, the age of a domain is worth nothing if there is no website attached to it much like an empty plot of land is just a plot of land regardless of whether it has been there for 4.3 Billion years