Normally, 'The Canadian' would serve that connection.
Its not very frequent (2-3x per week), even normally, its rather pokey; but it is there.
But its currently not running.
I don't think Toronto-Winnipeg is a particularly viable destination pair mind you; even if you got the frequency up to daily, its just not a remotely competitive trip time w/flying; and there's no path under which it will be either.
I'm a fan of shorter destination pairs, where demand warrants, and its practical to offer reasonable speed and frequency.
Thunder Bay-Winnipeg might make sense.
Sudbury to Thunder Bay might make sense
Toronto - Sudbury might make sense.
Toronto-Winnipeg is really pretty peripheral in terms of demand; its very hard to keep trip times reliable over that distance on shared track. So I expect that destination pair to really be served incidentally again in the future, as it has in the recent past.
The Canadian does not go near Thunder Bay.
My reason for the whole route is if you are going from Toronto to SSM, and then go further to Thunder Bay, it would be better to go to Winnipeg as it is the closer large city.
This potentially could happen if ONR owned the HCR and ACR. I know there would need to be some upgrading as the OVR has a speed of 25 mph, which is unrealistic. The connection through Sudbury is still there.
I'd doubt it would happen for at least 10 years after both HCR and ACR are owned by ONR. Even then, it would be doubtful.