US would do well to try to keep LH out of PIT. There is a reason why PIT is keeping the FRA flight. Notably, you have Bayer, Mannesmann Demag, Medrad, Seimens, and CONSOL Energy (owned by Rheinbraun A.G.). And the large ethnic population. If US dumped PIT-FRA, I''d expect LH to be in PIT.
Of course, US also had Marconi, GlaxoSmithKline, BNFL, and Invensys and let the PIT-LGW flight go as being "unprofitable." So you never know.