A few criticisms of the choice of Patchway, if I may. Sorry in advance if this riles anyone!
(1) The area is very well served by buses - so well served in fact that starting next Sunday one service will run 24/7.
(2) It isn't exactly unknown for longer distance services to call there, either due to diversion or due to some other factor.
(3) There are services around that could call there if required (Matt beat me to the post with this one, referring the Pompey-Cardiff service).
(4) Much of the demand is only to Bristol, by which time the need for a station - owing to its relative proximity - reduces.
(5) It is overshadowed by Parkway, which lest we forget is barely a mile away and has services to a wide range of destinations.
(6) If the Henbury loop does reopen, the one potential advantage it has - Cribbs Causeway - is lost to the new route. Ditto the Airfield development.
Sorry - Patchway really doesn't need a better service. If a second stopper between Bristol and Cardiff materialised, then I agree it should stop there - but unless this does happen, I really can't see any justification for an improved service.