The more I mull it over the more problematic I think Arteta leaving would be. He seemingly has a good relationship with the board and is working on a 'project' to implement his philosophy. He's cast off the big money players like Ozil, Auba, Laca, Pepe etc to do that and you'd expect his relatively young team to keep progressing under his tutelage. Apart from anything else, he's got Arsenal back in the top4.
If a new manager came in, it might take some time to reset and go in a different direction. I also think there's one or two players like Raya (assuming he joins permanently), Jesus and Zinchenko that are very much 'Arteta men' and might not work so well in a different system.
I say this against a backdrop of not being his biggest fan, but it would be good to harvest the fruits of his labour over the next couple of years.