Even prior to the rehab, the CM's at Living Seas were very very claustrophobic-friendly.
I asked to leave the wait area and decided to skip the attraction. An older gentlemen INSISTED that I couldn't leave without seeing Crush, and while he took me through the back route which bypassed the hydrolators, he also insisted on letting me stand at the back of the Crush show.
Then he had someone waiting to escort me out another back way and skip the exit hydrolators.
He was very sweet and even though I kept protesting that I was ok just to leave, he would make sure that I enjoyed my morning!! (It was very quiet and empty at Epcot that day)
I assume that the ongoing rehab will result in some form of the seacabs and/or hydrolators in future; in that case I would also just ask....
Hope that helps!!