I mean, no deader than it is right now.
Mueller's actual ability to do anything against this admin is minimal; as things stand, they have immunity by majority. All we can hope for is more political weight around their necks, making it easier to take back the House in 2018 and the Senate/WH in 2020. Firing Mueller adds a LOT of weight, possibly more than letting him investigate would do. Especially since you'd probably see a massive wave of leaks like we got from Comey.
We might lose the opportunity to indict Sessions, Flynn et al on whatever shit they got up to, but odds are good Trump just pardons them and then we're back to square 1 where Republicans refuse to perform oversight on a Republican president.