An Overreliance on Geth?

New to Ethereum here, but when looking at the Ethereum Mainnet Statistics from EtherNodes.org, it seems as if Geth clients account for roughly 80% of the total node implementations.

Could this be a cause of concern for Ethereum such that a flaw in this implementation (however unlikely) could cause widespread network effects? It seems to me as if a more healthy variety of node implementations would increase network robustness....

So if this is a valid concern, what is to be done about it? Is there a plan to promote other clients in some capacity?