I don’t even know if flood protecting the RH Line is worth it. The ridership on GO RH is totally pathetic. Just 10,000 people per day in 2016. That’s less ridership than the TTC has on minor bus routes like Midland, Birdhmount and Royal York. I can’t justify spending an much money to help so few people.
While I do agree that replacing DRL long with RER on the Richmond Hill line is an illogical pipe dream I must say:
Calling 10K people per day on a line with only 5 roundtrip services "pathetic" is extremely inaccurate. 1000 people use each directional train. That's quite a bit of people per train. It also gets about the same ridership as the Kitchener, Barrie, and Stouffville lines in terms of ridership/length (it is the shortest line in the system), and gets significantly more than the Lakeshore west/east, Kitchener, Barrie, and Stouffville lines in terms of ridership per train (average), the only one surpassing it being the Milton Line.
Compare this ridership to almost every other commuter rail service in North America. It does better than most lines in Montreal, and the West Coast Express in Vancouver.