Presumably the key to this is when the leicester area trackside signalling equipment is renewed, with whatever is done being set in stone for a generation, and I suspect one reason for reluctance to extend the wires north of Market Harborough for a while yet.
It was recontrolled in 2013 but that was, on the ground, just a largely like for like interlocking renewal I gather.
Four tracks through the Leicester area , presumably with an extra pair of platforms on the reinstated station goods lines is presumably a given.
I guess though with only four an hour each way heading south from Leicester and little if any prospect of that increasing due to, firstly no capacity south of Bedford and secondly HS2 east seeming to be pretty certain to appear as far as Trent Junction, a flyover at Syston is seen as a bit of an indulgence.