when do you think indoor mask mandates will end in ontario canada?

when the virus threat is over

Once more people get vaccinated and they become more widely available. Hopefully by fall or early next year. The vaccine plane is slowly being rolled out. Wearing masks indoors by law could be around for a while. 
If you don't want to wear a mask, order what you can on line to reduce your trips out. You should only be going out for essentials. 

when people stop getting severely sick from COVID.  Even when a majority of your area is vaccinated with the current vaccines, we will have to wait and see what new strains spread and if those vaccines work against them or not.

They won't end until vaccination is more widespread, so it looks like they'll be in place until the fall at the current rate. Different health regions might have different end dates.

Not for a long time.  Well after the last person is vaccinated - probably the Fall at the earliest.

I think it will end somewhere between next month and the next 3 years.  Thank you for asking, I guess.

Seriously, do you really think online total strangers know something about this pandemic that you don't?

Only after majority of the population has been vaccinated and new COVID-19 infection rates dips down to the point of being insignificant.

I doubt it will be anytime soon...

SLAP DOWN...
"Ontario COVID-19 lockdown: Province to shut down for four weeks as COVID-19 cases, hospitalizations rise"
https://ca.yahoo.com/news/ontario-lockdown-covid19-cases-doug-ford-vaccine-180041931.html