That’s your right, to unsub that is.
Just like it’s Blizzards right to make changes to their game.
Also, while you’re freaking out, they’ve also already announced they will be looking to find a way to bring Lone Wolf and pets back for MM, but their current idea is something different.
Leave the game if you want, the small amount of MM players that currently exist aren’t going to make a dent in their bank account so it’s doubtful they’d even notice you leaving. But y’all’s complaints have already impacted their decision, complaining more isn’t going to do you any good unless Blizz decides to back out of backing out and commits to taking away Lone Wolf and Pets.