"John B" wrote :
From conversations that I've had with Crossrail reps & BAA reps,
Crossrail is taking over the HC operation, and fares to Heathrow will
remain the same at changeover. This is because the Heathrow spur is
not part of the National Rail network, but privately owned by BAA. So
the answer to the question above is 'yes' (as it does now)
Hex is another BAA service & will continue (still charging a higher
premium).
...for a week, until it loses all its customers to Crossrail's
cheaper, direct service to the City and CW.
(seriously: if HEx is still running as a Heathrow-Paddington shuttle
when Crossrail opens, I'll eat an entire hat. Quite how they'll
arrange it to go through is another question...)

It may not be that quick (BAA are fairly stupid), but very few will change
from a crossrail heathrow stopper to catch a premium-priced 'express' for a
16 minute ride instead of a 22 minute one. It'll take longer for the folk
arriving at Heathrow to catch on that they are overpaying AND having to
change at Paddington.

The options are either a few crossrail trains going fast to Heathrow after
Paddington, or no HEx.

Off course, BAA will want to keep the Golden Goose going as long as
possible - but a half-empty peak hour HEx won't be very profitable, I
suspect.

If you look at total journey time, only someone living on Platform Five at
Paddington will gain much more than 5 minutes by HEx-ing; too few to
maintain a premium service, I suspect.