Post HS2, a potential idea could be to open a new (not on the old alignment) dead straight, 125mph line from the WCML south of Rugby to the MML south of where the line from Nuneaton joins. The fast services from London to Leicester and Loughborough would then be provided via the WCML, and additionally these places would be connected to Milton Keynes (I would have everything on the WCML fasts stop at MK post HS2). I would anticipate journey times to Leicester being roughly the same as MML timings - between 1h and 1h10m.
The MML service would be reduced to 2tph Corby (Luton Airport, Luton, Bedford, Rushden, Wellingborough, Kettering) and 2tph Leicester (Luton Airport, Luton, Bedford, Wellingborough, Kettering, Market Harborough). The only loser with the scheme would be Market Harborough, losing its 1tph nonstop to London.
The junction with the WCML could be a triangle junction, with the XC Birmingham to Leicester / Peterborough / Cambridge fasts being provided via Rugby (additionally connecting these places to HS2 via Bham Int, providing connectivity from these stations to Manchester, Liverpool, Preston, Glasgow etc, and reconnecting Leicester with Coventry, a link often suggested to be reinstated due to high demand) and the line via Nuneaton could be transferred to WMT and become a commuter line with lots of new stations and no services past Leicester.
I’m struggling to understand the sense of any of this.
Particularly the high demand Leicester to Coventry. As a former commuter on the line when there were direct trains, the number of regular commuters per train travelling between the two cities could easily be accommodated on a small bus.