I agree with Peter. The tracks and switches are still in place, just not Revenue ready.
Cosmetic work is necessary if the LL platform were to be re-actvated.
The switches are still in place, though made in-operable.
For the sake of fantasy, a diamond cross-over should be installed between the 8th Ave local track and lower level track serving 50th and 42nd and a second diamond crossover between the lower level track serving 50th and 42nd and the 8th Ave express track.
This would give that needed flexibility when the "A" should go local or the "C" should go express from 42nd St. south to 23rd or Canal.
I'd favor rush hour use for the "E" and layup (2 trains) during extremely cold weather. An additional escalater to the mezzanine would aid those P.A. Bus users.
avid