Why should anything be predetermined? Why can't we take a reasoned, informed, overal view of our transit system and make choices based on what's best for that particular area. Instead we are making political choices based on things that have very little to do with transit service.
I thought I made my point. The 2 Finch routes will not see any difference should the subway extension be built, they never ever tread onto Yonge St. The 2 Steeles routes would be most affected but I'd imagine that they'd run more or less express along Yonge anyway. 125, and 42 are on Yonge for what all of a block? So what benefit are they going to see. The 97, also, will still trundle along Yonge regardless of any subway expansion and will not be affected by it in any meaningful way. We've got subways being built where LRT would suffice, LRT being built where really subways should be and where busses (or BRT) would suffice, etc, etc, etc.
If an LRT is built long enough (As I said earlier to Richmond Hill Go or further), it will collect many more riders from surrounding feeder routes and bring them down to the subway quickly. It could replace many if not all of the YRT busses currently running down to Finch.
Anyway your post proved my point, subway was selected before selection began and the options (option really) considered were chosen because they would obviously fail in comparison to a subway.
You don't really have a point, not one that makes much sense, anyway. Every project is predetermined and studies "examine" "alternate" "options" (including the ever popular 'do nothing') that are immediately discarded to "justify" predetermined choices. That's how these things work and that's how it would work if an LRT line was chosen. It'd be great if transit studies always selected the option you prefer, but tough luck. There is no objective way to plan transit...politics and all kinds of subjective city-building and common sense factors come into play as much - and sometimes more than - the nebulous 'informed reasoning' you're looking for. Of course, your opposition to extending the Yonge subway into the 905 is based, in part, on politics, so...
An LRT line is not a substitute for a subway extension. A subway extension is inarguably the only serious option north of Finch. It is absolutely necessary. Where it terminates, though, is debatable. York Region, its municipalities, and the province have made transit and planning decisions that make Hwy 7 the best place to terminate the line, and not some place north or south of Hwy 7.
You don't seem to be understanding what would happen to the bus routes in each scenario. With a subway extension, routes like Steeles and Cummer would not continue down to Finch, and neither would the YRT routes (though some will continue along Yonge for a bit north of Steeles to get to the ridiculously massive Steeles station). The mileage and frequency of buses plying Yonge would drop dramatically. If they built an LRT line starting at Finch and going north, buses like Steeles and Cummer would continue on to Finch and not terminate at an LRT line a few blocks away from the subway (and if they did, ridership would plummet). Some YRT and GO routes would do the same (though YRT routes are more malleable)...how would an LRT line on Yonge replace, for instance, the Bathurst, Milliken, or Bayview bus? It wouldn't.
The 97 could very well be eliminated, but what's more likely is that it would replace the local service previously provided by, mainly, the 53...it could then support service a bit better than every half hour and the buses wouldn't run nearly empty. Every metre of bus route replaced by a subway extension is fantastic and productive, especially when so many routes inefficiently overlap north of Finch and when bad traffic - worsened by the buses themselves - is a problem.