With Raanta, and a bit less so Darling, opposition will start to make book on them soon, if they haven't already (a.k.a. the reason for the sophomore slump).
Asking Raanta and/or Darling to work through that all the while having to not only bail out the newcomers' mistakes, but the mistakes that are core is won't to make, might not be the wisest move.
At least Crawford has done that before and shown some success--maybe not as much as we the fans would like.
Ultimately I think if you're going to break in a new or sophomore goalie, you have a strong established D-core. If you're going to break in new D skaters, you have an estabished goalie. You don't do both at the same time and realistically, next season Hammer, Keith, and Seabs is all we've got going into it. If Raanta, Darling, all of the new D-men, all of the new O-men, and even the offensive core proper take a field day defensively, those three are going to be driven harder than a rental car when you pay the "anything happens, you walk away" insurance.