MP Shop Weapon Rotations

I'm suggesting to remove/change permanent MP weapons after one month and add in something new just so the weapons available for permanent don't become to common and useless. The hunting knife is a perfect example of what I mean. It used to be my favorite knife because it has a cool theme to it and super rare but now I have 3 and I never use them

I'm hoping the same thing doesn't happen to the new MP weapon.