Normally, I would think that the sub could be salvaged, however the San Francisco was commissioned in 1985, and while she was designed for about 30 years of service, the Navy has been retiring a number of LA class SSNs when they reach around 20, and they have more retirements planned for the near future. If the San Francisco wasn't planned for decommissioning in the upcoming years, I wouldn't be surprised if the Navy chose to retire the SF in place of another more healthy submarine.
I just read that the San Francisco was scheduled to be decommissioned in 2017. If this is ture, the Navy might try to repair the damage, since she'll be good for another 12 years or so. Although it might take some time to repair that kind of damage; it would involve essentially building a new nose section.
Does anyone know if it would be practical to take the nose section of a LA sub scheduled to be scrapped and fit it on to the San Francisco?