Yes Colorado has to battle their own folks but take a look at what resident hunters are saying, they will pay more and lots of way to make up that shortage especially in Colorado.
There are plenty of folks with the money to pay the high fees.
Saying that CO residents will close the budget gap and pay hundreds of dollars more per tag tag is a purely anecdotal opinion of yours. The small town and rural guys I know can't afford to pay that amount for themselves (and x2 for many of their wives) to hunt elk, deer, and pronghorn. The people in Denver, Boulder, and COS can perhaps afford it, but these aren't the hunters, as evidenced by their history of endorsing anti-hunting measures.
The folks on the Western Slope are the hunters. Right now, they can draw an elk and buck license for $170 all in. The NR pays $1406 for the same licenses, $1236 more. This is my opinion, but I view your opinion of "There are plenty of folks with the money to pay the high fees" as flat out wrong.
I agree that CO and others do not "need" non-residents, but they will need to reduce their budgets drastically if that's the route they want to go. Future conservation efforts and improvements will slow down or cease.
And to all of the small town stores/restaurants, motels/lodges, airports, outfitters, etc., just ask them how dependent they are on hunters during the fall. And the local tax revenue that contributes to the town's operating budgets. Hunters/anglers, largely from out of the state, generate $3.25 billion for CO and support more than 25,000 full-time jobs across the state. Again, the economic impact is not just limited to the sale of licenses. Anyone who doesn't recognize this is tone deaf.