I don't like it at all. Tennis is becoming a marathon contest, where touch, creativity and flat-hit winners are almost non-existant.
Easy solution would be to go back to "worse" racquet and string technology. That way it would be inmensely more difficult to hit passing-shots or retrieving shots (like it was in previous decades, giving an edge to the player who attacked first in the point).
They will never do this, I am sure of that (strong racquet and strings commercial profits).
If they mantain current racquet and string technology, and they speed up the courts, or at least some courts, we would see at least some variation, but you would have the "problem" of having an Isner or Karlovic type of player winning 95% of first serve points by ace or unreturned serves.
Goran and Krajicek (among others) used to be like this, but these players always would be a minority, so I don't think it would kill the game appeal.
But I think they are going to slow down things even more because they think casual viewers like extremely long rallyes, but many of the beautiful and interesting things about tennis are missing this way.