Eventually, yes.. But you act like there aren't ways to pay them even though, every year, we see teams who are "in cap hell" cut $20-$30 million off their cap, sign players they need, and move one without too much of a hiccup.
The Broncos could easily pay Welker, Thomas and Decker if they wanted to. Thomas will get top money, but Decker won't. Not as a #2 there in Denver. Maybe with someone else, but unlikely.
Also, the devil is in the details. They could structure the contract in such a way that they go up once Welker was gone..