I think this update has done exactly what they set out to do.... I am no longer able to use a droid team and one-shot people into oblivion or an all jedi team with QGJ leader in the same manner. This has forced me to think outside the box on how I approach certain teams. I have since been able to find new uses for heroes i have neglected because they can now survive a bit more. I would congratulate the developers on the improvements of the game and encourage them to keep up the good work.
As for the players struggling to succeed, this is a grand opportunity for you to come up with new ways to win and a new "meta" (I use the term lightly). If you are going to delete the game because the old speed meta was nerfed, then you fail to see that the point of an update is to make the game balanced.
May the force be with you!