Mind you, the nearest LH hub is not FRA, but BRU which is better located for connections to Europe and the US than further away FRA, not to mention MUC or ZRH.
Already today, BRU seems to be the preferred connecting point within the LH group for all flights from the British regional airports to Europe and the US/Canada, so I wouldn't be surprised if BD/SN start a GLA-BRU flight on E-jet, if indeed LHR-GLA get axed.