Scanning using the old models/designs and updating them would also be acceptable.
No way they will look as bad as the mid 90's cgi that made its way in star wars special edition.
I think there is zero chance of anything other than cgi though since the JJ Enterprise was completely computer generated by ILM.
Only certain shots in the Next Generation films of the Ent E were of a small model. They never built a full scale like the refit/ 1701 A.