It was more in response to some who think any train that enters the GTA must take on a commuter role. Having a north-GTA stop would just be a way of easing those passengers coming from/going to non-downtown locations. I honestly don't know if passenger demographics would support this.
I think that depends on what you mean. Nobody is going to commute from North Bay to Toronto everyday. But what if you have a meeting in Toronto or a hospital appointment?
Now I think that with the droves of people who have moved out of the city and moved to Muskoka during the pandemic, they may still have jobs in Toronto. So that's where a realistic Commuter market would be (South of Huntsville). If you can get on at Huntsville at 6 and be in Toronto for 8:30 and only need to do it once or twice a week then it's very much doable. The other thing is for those living in Muskoka to visit Toronto for a weekend, or continue on to Montreal or other places.
Not to mention the weekend crowd to cottage country, which is why GO Transit has more service to Barrie on weekends. But one train in and out each day makes it tough, since if you miss it, you are SOL. Four trains in each direction (Two in the AM, two in the PM) would be ideal so that a train leaves Toronto and North Bay so that you can leave first thing in the morning and get to the other end by 8:30 am. Considering that the UP Express starts up around 5am means that you could have a Northlander Train leaving Union at 5am, which would get you to North Bay around 9am. The key would be bus connections along the way at each stop to make it easier to get customers to their final destination.
So partnering with Hammond Transportation to help people get from Washago to Penetang/Midland or to add stops at Langstaff and Gormley would help since if you live in Gormley you dont need to take the GO train down to Union to catch the Northlander back up to Bracebridge or wherever.