Thats not true right? If one of the two surfaces which are similar anyway disappears the effect is very small - and should not have material effect on player's results -- unless you had players who were very good on one of the surface and poor on the other -- and vice versa.That's neither here nor there. When it boils down to it, any surface X can be said to play "almost like" another surface y.
The point is: Less variety of surface = greater homogenisation.
For a contrary example, we know clay and hard courts play quite differently. If clay disappears then yes, you could say homogenization has happened.