While I agree we need to eventually do that, the cost of updating the track (and particularly the bridges) for the whole route is making it expensive. Just get the langford to downtown portion up and running to prove (like it needs proving) the concept. Once it is operational then it can be expanded upon in sections, go to Duncan, cowichan valley, etc and move up island. The priority should be alleviating the colwood crawl.
When is the last time you actually went on the e&n bike path? It's parallel to the railway line, the tracks are still there. Additionally, Victoria has the highest proportion of commuting bike riders in the country thanks to our mild weather a decent bike infrastructure. Every one of those bikes on the path is a car not on the road.