the reward for supernode is getting smaller and smaller, just 654xem today 
This just means that the program is successful.
The goal of the campaign is increasing the number of good nodes to make the network rock solid, not making the rich richer.
To prevent this you should encourage new users to run a Supernode. There should be good tutorial material in order to make it as easy as possible to let everyone whos interested to set up a supernode.