It will be interesting. The first three are good enough, but if (or when) one of them gets hurt it becomes "Anything can happen day*".
I think Clark makes the team, getting one more year to learn the game. They seem pretty high on him.
I expect that Davis will have to make the team as a receiver. There are now other options at kick returns, and his developmental spot will go to one of the new kids.
Yancey should have a good chance as he has a years experience and they will need someone to fill in now and again. As psico noted, experience is going to be at a premium.
* Mickey Mouse Club on Friday. My favorite day as you got an extra cartoon.