I recently read a Kirsten Beyer Voyager novel where the USS Quirinal, a Vesta-class starship, crashed down on a planet. After weeks of repairs the ship was made spaceworthy again. So I'm kind-of prepared for the idea of the Enterprise being salvagable.
As for a refit - it's possible. If not at the end of this film, at the start of the next. Star Trek XII
will likely have a new director. And they just can't resist changing things! Look at the Enterprise-A in STIV, V and VI. It's meant to be the same ship, but goes from shiny white ultra new, to a bigger TOS/TNG hybrid with touchscreen controls and carpet, to dark and worn out, no carpet, with push-buttons again. Star Trek
and Into Darkness
may be the only two Trek films where the ship and sets look 100% identical between them!
I really like how the Enterprise looks as-is. If they do refit or replace her, it'll be a shame.