Well, unless they've got a clause in the contract that says they can terminate the deal upon relegation, or significantly reduce payments. A lot of sponsorship deals and even players contracts have clauses like this. There's a huge drop off in terms of viewership between the PL and the Championship so that is often reflected in the various deals and deals can be lost upon relegation or payments significantly reduced. It would kinda be silly on the sponsors part not to have them really. The PL is the most watched league in the world, whereas the Championship probably doesn't get much attention in the grand scheme of things, so that's a lot of eyeballs missing and less eyeballs means less exposure for your brand.