Dallas and San Francisco are in the same boat. Their quarterbacks are not elite but they'll have to pay them elite money. Sure, they can be pretty good if they have the offensive line, running backs and receivers. But they cannot make up for any shortcomings in those areas.
We might see Dak's play decline this year. The running back situation isn't good. The line isn't what it used to be. After Lamb they don't have much at receiver. Wouldn't be surprised if Dallas doesn't reach double digit win total.
Purdy still has high level skill talent around him, so he should be able to continue to play at a good level. At least on paper he has elite talent. But it sure looks like Deebo's best days are behind him. McCaffrey's at the age where heavily used backs start to decline. Kittle's 31 years old. Aiyuk might get signed eventually. But he might miss a few games before it happens. Its gonna be tough for them to repeat last year's performances.