Lone Wolf (mostly for me to avoid the crappy pet pathing in game) as an option has always been fine, no need to remove it and force players to lose pets when in MM.
Also bring back ranged SV and make a new mail melee class that offers a pet and petless spec, or add a melee class to hunter.
It is beyond ridiculous that a class that started as a ranged pet CLASS may now be a class with a ranged pet spec, a melee pet spec, and a ranged pet-less spec.