It is possible that the insurance company will want to right it off, however, they will still be obliged to pay out the value of it. It is in their interest to get a good deal for you as it will be claimed from the guy who ran in to the back of you, as will the personal injury claim.
You definitely want the option to buy back the vehicle, either for parts or project, as the money from the claim should more than cover the cost of repairs. Or sell parts and the joint sum for a faff.
Hope you manage to get it sorted ok, feel free to give me a shout if you need any tips/advice.
Cheers