On Mon, 29 Aug 2016 03:22:45 -0700 (PDT), Chris
wrote:

On Sunday, 28 August 2016 19:05:57 UTC+1, e27002 wrote:
Guy,

It is intended to be a four track mainline. The fasts to Birmingham
would use the fast pair. The stopping service to Aylesbury, and
Milton Keynes would use the slow pair.

If you had read NR's latest Route Study, you'd notice there is NO mention of a four track railway - even to 2043.
Yes, some services are likely to go to OOC, both from the Mail Line & the heartlands stations, which would free up a platform or two / paths from Northolt top Marylebone. This won't help the Metro stations as there is nowhere to start a metro service from - the Ruislips will still need to handle all the services....
Chiltern have no interest in more Metro services as TfL won't pay for them.

So, I was basing my comments on the news item on pages 20 and 21 of
the July Modern Railways.

You are correct: When one reads the actual study, page 71 reads
"Additional track sections through Beaconsfield, Denham and Princes
Risborough to create four track sections in the
station areas. Reconfiguration of the layout at Princes Risborough
Station to extend Platform 1 and create movements
in both directions for Aylesbury services into and out of Platforms 1
and 2."

Which indicates some restoration of the platform loops removed by the
nationalized railway. An improvement, if a lessor one.

As for metro services these can be raised at franchise renewal time.
Residents should consider contacting their MP(s).