Here's hoping for some infrastructure enhancement and the operation of services towards Old Oak Common. It would prove particularly handy for the punters. That said, you'd need to remodel Northolt Jn and South Ruislip all over again.
Would be grand to see a four-track as far as High Wycombe so that a better Metro service could operate. Also four-track Leamington to Moor Street. Would also like to see the opening of new platforms at West Hampstead (somehow), the transfer of operation of a High Wycombe to Maidenhead service and new homes at Loudwater to Chiltern, new platforms at Greenford on an upgraded New North and the operation of East West Rail Link services from Princes Risborough to Milton Keynes every 30 minutes and no direct through long service via Wycombe as it is frankly pointless and creates conflicting moves at Risborough. Also the transfer of the Oxford to Banbury stopper to Chiltern and the extension of that through to Coventry; as there is insufficient pathing for a Leamington to Nuneaton apparently! Kenilworth therefore gets a through train to Banbury and Oxford.
E.g.
2tph Old Oak Common - High Wycombe
Old Oak Common, Greenford (new platforms), Denham, Gerrards Cross, Beaconsfield, High Wycombe.
2tph Marylebone - High Wycombe
West Hampstead, Wembley Stadium, Sudbury & Harrow Road, Sudbury Hill Harrow, Northolt Park, South Ruislip, West Ruislip, Denham, Denham Golf Club, Gerrards Cross, Seer Green, Beaconsfield, High Wycombe.
2tph Marylebone - Moor Street fast
West Hampstead, Banbury, Leamington Spa, Warwick, Warwick Parkway, Solihull, Moor Street.
1tph Marylebone - Snow Hill semi-fast
West Hampstead, Beaconsfield, High Wycombe, Saunderton, Princes Risborough, Haddenham & Thame Parkway, Bicester North, Banbury, Leamington Spa, Wawick, Warwick Parkway, Hatton, Dorridge, Widney Manor, Solihull, Moor Street, Snow Hill.
2tph Marylebone - Oxford fast
West Hampstead, Princes Risborough, Haddenham & Thame Parkway*, Bicester Village, Islip*, Oxford Parkway, Oxford.
*One of the two trains an hour.
1tph Marylebone - Stratford on Avon
West Hampstead, Gerrards Cross, Beaconsfield, High Wycombe, Princes Risborough, Bicester North, Kings Sutton, Banbury, Leamington Spa, Warwick, Warwick Parkway, Hatton, Lapworth, Claverdon, Bearley, Stratford Parkway, Stratford on Avon.
4tph Marylebone - Aylesbury Vale Parkway via Amersham
West Hampstead, Harrow on the Hill and stations to Aylesbury Vale Parkway.
2tph Princes Risborough - Milton Keynes Ctl
Local stations to Aylesbury Vale, Winslow, Bletchley, Milton Keynes Ctl.
1tph Oxford to Coventry
Oxford, Tackley, Heyford, Banbury, Leaminton Spa, Kenilworth, Coventry.
Transfer Leamington to Moor Street stopper into West Mids Railway. Therefore WMR offers:
2tph Stratford on Avon to Stourbridge Jn
2tph Whitlocks End to Worcester area
2tph Leamington Spa to Kidderminster
2tph Dorridge to Kidderminster