Thank you Stuving and Paul for your informative comments on this.  It makes sense that this proposed change is stopping pattern is a result of the recent announcement about service increase. 

I had seen the map highlighted by Stuving mentioning that no Heathrow trains would stop at West Ealing, which would have created fairly nonsensical situations especially for people travelling on the Greenford branch.  Some local Ealing Lib Dem councillors had also organised a petition to TfL^» (Transport for London - about) recently when it was announced (I don't know by whom since I never saw this announcement!) that after Crossrail, trains from West Ealing to Heathrow would reduce from 2tph currently to 1tph (vs. 0tph on the map pointed out by Stuving!).  TfL then responded to the petition by saying they had no plans to reduce the level of service between "West Ealing, Hanwell and Heathrow" from that which operates currently, and the petition was closed.

http://www.ealinglibdems.org.uk/westealingtrains

With information on the final timetable coming in bits and pieces from different directions and sources, this is all fairly confusing at the moment.  But I guess not altogether surprising given the complexities involved in putting together a final timetable which works in the best possible way.

Hi everyone - I'm new here, please go easy on me 

I've been silently following this thread for some time.  In my spare time, I have also recently visited the London Mayor's Question Time web site.  In a document titled "Answers to Questions Not Answered at Mayor's Question Time on 14 September 2017", Sadiq Khan mentions something which I had not seen anywhere else before, namely that from December 2019 onwards (once the last phase of the Elizabeth line opens), the intention is that at peak times, there will be six trains per hour stopping at Hanwell, and ten trains per hour stopping at West Ealing when travelling into Central London. 

If true, this is big news from people living near Hanwell and West Ealing stations.  Some of the information released to date, e.g. still on the official Crossrail web site as of today, mentions there would be only four lines per hour stopping at those stations from December 2019.  I don't know what other implications this might have for the timetable of the rest of the line, the off peak timetable and the timetable applicable between now and December 2019.  I also don't know if one can take this as a "fait accompli" or rather a non binding suggestion of the mayor (or TFL^▸ (Transport for London)?) which may or may not happen in practice.

The full question and answer, together with the link to the Mayor's Question Time web site, are included below for reference.

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Crossrail Frequency
Question No: 2017/3713
Onkar Sahota
Further to MQ 2013/2656 & MQ 2013/2657, and given the considerable interest and concern that local residents along the route have for the future service they should expect from Crossrail; will the Mayor give reassurances to commuters using Hayes & Harlington, Southall, Hanwell, West Ealing, Ealing Broadway and Acton Mainline stations that they too will benefit from increased services at their stations as a result of the extra trains per hour being laid on West of Paddington; and will he confirm to me how many trains will serve each of these stations per hour in both directions?

Written response from the Mayor received 10/11/2017
I am pleased to say that following a review of the timetable, services on the Elizabeth line are set to be even more extensive and frequent than originally planned. This also includes plans it
to call at Terminal 5 - meaning all Heathrow Terminals will be served by the Elizabeth line.

A total of six Elizabeth line trains per hour will serve Heathrow Terminals from December 2019. Four will go to Terminals 2, 3 and 4 and two will go to Terminals 2, 3 and 5. Services will also
increase to Ealing Broadway, Southall and Hayes & Harlington. To facilitate the increase, the number of trains that will operate on the line will rise from 66 to 70.

As Elizabeth line services share track with other national rail services, TfL^» (Transport for London - about) is working closely with Network Rail and other operators to agree the final timetable and service frequencies.

However, from December 2019 the intention is that customers from Acton Main Line stations will have four trains per hour, Ealing Broadway will have 12 trains per an hour, Hanwell will have six trains per hour and customers from West Ealing, Hayes & Harlington and Southall will have 10 trains per hour at peaks when travelling into central London.

The full timetable will be confirmed closer to the start of services.

Source:
https://www.london.gov.uk/moderngov/documents/b16054/Appendix%203%20-%20Written%20answers%20Thursday%2014-Sep-2017%2010.00%20London%20Assembly%20Mayors%20Question%20Time.pdf?T=9