@Urban Sky was a bit more snarky than I was going to be..........
But he's on point.
The average running speed for the Shinkansen from Osaka to Tokyo is ~200km/ph or thereabouts. Sure its peak speed between stations is much faster, but the trip time has acceleration/deceleration and dwell time.
If you apply that to Toronto - Sudbury, assuming a completely new, straight as possible line ROW, only moving out of the way of major inlets/bays etc. You have a distance of ~350km to cover. That would put your best possible run time at ~1 hr 45, rather optimistically.
Translating the price for that train from Japan, I get about $127CAD 1-way for 500km, assuming, you could pro-rate that to the shorter 350km distance, you're at $88.90 one way, assuming a 10% discount on a round-trip, you're at ~$160.
That there is some seriously pricey commuting.
Again, this is maximum speed, not average operating speed. I imagine with few stops, you could drive average speeds a bit higher than is currently seen in Japan, but I wouldn't imagine one would see much better than a 25% improvement in the foreseeable future.
Sure, that would knock down the super-optimistic commute to 1hr 20 at a push. But that's borderline fantasy and the cost of getting that done would be astronomical.
I'm happy to favour restoring more City-Pair rail services in Canada.
I'm happy to consider subsidizing CP/CN to improve their trackage, and straighten some bit of alignment (or build partially new ROW if one can get competitive times and utility from that.
But that would not deliver Sudbury-Toronto as a commuter line.
Also if one was to shell out that kind of dough, beyond the mainline corridor in Southern Ontario/Quebec it would logically be to extend existing commuter runs just one city further (ie. Barrie to Orillia by dropping commute times) or Stouffville to Uxbridge/Lindsay; or of course to other logical City-Pairs which would be Edmonton/Calgary.