Well, if they where scheduled to skip chorley that would make it easyer in times of divertions via Wigan / Westhaghton.
4 track would actually also be possible at moses gate station, bit of re-modeling needed, but all possible, and this 4 track could also be extended proberbly as far as chorley, a logical end point would be Horwich Parkway, or in fact Chorley, would be a lot of work replacing the ticket office but could be 4 trakced through chorleyto finish on the north side of chorley before the arches, and then be able to terminate commuter services there, Horwich Parkway would be a lot easyer as a terminus though, and would make sense, as BPN services call there and are then fast to Piccadilly. Possibly divert the moses gate, farnworth, kearsley stopper to terminate at some shiney new platforms at Horwich, hence making it electric, and a hell of a lot easyer to keep out of the way of expresses, being quicker to accelarate.
But, also, the Lostock Jcn - Wigan South Jcns line should be electrified. not much line and then all but two services of the eight current services through bolton would be electric. (Barring Airport - Southport and Victoria - Clitheroe) and would provide a diversionary route when Lostock to Euxton Jcn is closed. And then with all these electric services running at about the same speed, thats going to free up some capacity to fit in the scottish services and keep them seperate from the commuter ones. So for example as a timetable:
Airport - Blackpool N 1tph (Picc, OR, Deansgate, Salford Cres, Bolton, (Lostock), Horwich, Chorley, Preston, etc.) (Leccy commuter)
Airport - Lakes 1tph (Barrow/Windermere alternating) (Diesel 185) (Picc, OR, Salford Cres, Bolton, (Horwich), Chorley, Preston
Airport - Scotland 1tph (Glasgow/Edinbrugh alternating) (Please be tilting leccy stock!) (Picc, OR, Bolton, Preston)
Airport - Southport 1tph (current stopping pattern + Lostock)
Airport - Horwich Parkway (using the current Airport - Piccadilly and extending to Horwich Parkway, all stations to Salford, fast to bolton, lostock, horwich)
Hazel Grove - Preston (Current pattern, move to commuter leccy)
Victoria - Blackburn / Clitheroe (as is), possibly extra services on Wigan - Bolton - Blackburn, most pepole change off for an airport train at bolton anyway
Victoria - Blackpool N (as is)
Victoria - Wigan Wallgate 2tph (as is)
Victoria - Horwich Parkway stopper 1tph
I don't think 11tph is too much to ask?
maybe some significantly larger car parks? Horwich Parkway is rediculously small, and theres a nice big chunk of land on the operside side of the tracks, they wanna have a P&R to take the strain off the M61, put a massive car park in then!