Thanks for putting the link up, Paul.
Crossrail to Reading is an absolute no-brainer. Always has been - surely it's just a matter of time.
As for the HEX service, I've said before:
I also have my doubts as to whether there will be enough of a demand for HEX trains after Crossrail starts - I would have thought it better to have more trains through from the east of London direct to Heathrow than have them starting at Paddington. Certainly not every 15 minutes anyway.
I really can't see that HEX can or should survive in its current form. Given the huge numbers of trains that will go no further west than Paddington after Crossrail starts, I'd have thought that getting rid of the HEX service and having Crossrail go to Heathrow twice as often would be a better service - even if the actual journey time is lengthened a little. It'll be tricky to timetable the service, but the paths released on the main lines would be such a boost to capacity as Reading would by then be able to handle another 4
HSS▸ trains per hour.
Then the Class 332's currently used on HEX could get a refurb and go up north to join their cousins, the Class 333's, giving the Leeds area a boost capacity wise.
As for extending Crossrail onto the
WCML▸ . Good idea. Not a great deal removed from my old suggestion here:
http://www.firstgreatwestern.info/coffeeshop/index.php?topic=4207.0
My original suggestion of Crossrail going onto the Chiltern Line has been somewhat ruined by the
HS2▸ plans (although it does get a brief mention in the document), but there's no reason why the alignment from Paddington I suggested couldn't be similar until it dives off north to join the WCML. Much better than having 14tph (still at least 10tph even if HEX is replaced with Crossrail) arriving at Paddington from the East and going no further!
Lots of hurdles in the way, but I'm glad the thoughts are there!