Extending it past Langley doesn't make sense from a capital cost point of view, and the fact that all the area east is a different transit region. It creates a complexity that TTC/YRT does in the Toronto metro area. The WCE is similar in that regard, let's say that a separate WCE line went from Cloverdale (Surrey) to Langley so that there are no bridges to cross trying to get it to a rapid transit/airport terminus like Bridgeport, and then that line follows the previous Interurban "Central Line" to probably Chilliwack.
(Side note, the interurban used to connect with a logging railway that went all the way to Chilliwack lake
http://forums.clubtread.com/11-hikin...tml#post136536 , if you look at the ALR map, not much of it is in the ALR
http://www.alc.gov.bc.ca/assets/alc/...ap_92h_001.pdf . )
Back on topic though, I think we're looking at least a century before major developments end up going that far. In
1891, Burnaby was all forest, and the Interurban central park line, literately connected through Central park which was in the middle of the forest.
So the question really should be, where do we want people to commute from, rather than "what would be a scenic ride", or vanity projects which seems to be the problem every time reviving the interurban comes up.
There are political consequences if Surrey is allowed to build a LRT, because they may seek to carve out their municipality from Metro Vancouver, and thus complicate all development in the Fraser Valley. Since Langley is to the east of it, without the Skytrain being extended first, Surrey may never allow anything but LRT's to be built, thus the only way Langley ends up with rapid transit is by extending the Skytrain over to Poco, through Pitt Meadows. That's a much less convenient trip if your destination is anywhere past Coquitlam.
Which goes back to the issue with Heavy Rail/Commuter rail. Let's say for the sake of not wanting to go around in circles again, that Surrey builds it's LRT, withdraws from Translink and then expands it into Langley, and Langley doesn't want anything to do with LRT, and instead wants to be the terminus of a Central Fraser Valley commuter line. We're still left with this gap between the Skytrain terminus and Langley.
Ideally, the Skytrain is extended to Langley, and Surrey can no longer dictate anything to the Fraser Valley. If a commuter rail is then proposed, it could go all the way to Scott Road station (I believe that is the closest) over the existing SRY. But that still requires Translink being able to acquire the SRY. Which since Translink doesn't really have anything to do with the Central Fraser Valley transit area, that may require expanding Translink's area to the entire Fraser Valley, or operating the SRY/Interurban as an independent operator.