I'd like to believe that. But according to the Georgetown South project website that "only a fraction" is actually 140/185.
Here's what GO Transit's GTS page shows:
http://www.gotransit.com/gts/en/faqs/default.aspx
------------------Present--- 2015
Daily GO Trains ---- 14 ---Up to 29
Airport shuttle------ 0 ----140
Via and CN-------- 10----16
Total---------------24--- 185
This is what GO has been planning from the start. So there might be more express peak trains (as well as converting existing trains to locals), and maybe some shoulder-peak trains, but not even close to present Lakeshore Line levels. Now, with VIA cutting back thanks to Harper pulling subsidies, the CN/VIA number will change somewhat. The chart has been updated to read Kitchener Line, so nothing's changed there.
There will be 3 or 4 trains an hour, each way, 18-20 hours a day, on the ARL premium line. There may be only 3 or 4 extra GO trains total in each direction that Westonites could board (presuming that GO runs express trains making last stop in Brampton or Bramalea before Union).
Maybe further down the line all that work could be of actual benefit to Westonites, but not in 2015.