If they let Pollard walk and get rid of Zeke they will almost certainly have to pick a RB in the first few rounds. Robinson, Davis, [insert UDFA RB here] would be a more than acceptable group.
I really think the most likely scenario is that Jerry is going to resign Pollard, convince Zeke to take a significant pay cut (I get the feeling that Zeke has made his money and wants to see this thing through with Dak), and roll with Malik Davis as your third again.
I can't help but think we would be better served letting Pollard walk and adding a difference maker like Robinson, but Pollard has been lightning in a bottle and I can see the temptation to bring him back on good money.