There's even a convenient toggle in the settings for going back to all the 2.79b keybinds. Muscle memory shouldn't be a reason to not upgrade.
It's going to bring in more users than it alienates, and those that are upset about the change can always easily switch controls to "Blender Classic" in the preferences.
New users don't know how to fix the behaviour. They just leave.
This change also has received some backlash from the existing userbase, albeit you can configure the behavior.