They can't assign you a trip outside your footprint (although they can using phony deadheads) without you volunteering. This is just pre volunteering. They can still revise you out side your footprint using the old 150/200 rules. Its really not all that different from the old contract, just a mechanism to let Crs know that you are willing to volunteer which they used to have to ask you.

If you don't pre volunteer they can still ask you and you can either turn it down or accept.