You do realize Dak can't play forever, right? Not only that, as he continues to age his play is going to spiral down the drain, and in fact he's already lost a lot of mobility due to injury from 2020. Eventually the team will have to move on, so there's no point being scared about the unknowns and life without Dak. The Cowboys franchise won't get sucked into a giant black hole just because Dak left the team.
Let's say you have a crappy car that's on its last leg. You have had this car for 10 years and have grown loyal, but you know the end is near. For some reason you stick with this car because you are afraid that the next car won't last 10 years like the last one and one day you end up broke down on the side of the road. Do you see where I'm going with this?
Don't be afraid of life without Dak. You will survive.