My guess, if anyone picks it up, it would be TSN...
I suppose it's not completely impossible, but there hasn't been anything stopping TSN or Sportsnet from acquiring Canadian TV rights for it if they had wanted to, in the same way TSN shows Nascar and F1, and IndyCar on Sportsnet. Even now with their multiple channels, I doubt they would show all or most of a 24 hour race. I think TSN showed some of it (from ESPN) in 1988 when the Andrettis drove a factory Porsche.
Realistically I think the most likely situation will be that it won't be available in Canada on a TV channel.
"services other than mainstream sports services are generally subject to a condition of licence limiting the amount of live professional sports programming they may broadcast."
"Limiting the amount" seems to be a little vague as to whether it would apply to this hypothetical case, or anyone would care. Since the "mainstream" North American sports channels (like TSN, Sportsnet, and their U.S. counterparts now including Fox Sports) have shown no interest in acquiring the TV rights, is this a mainstream pro sports event, or a niche thing? Who would complain to the CRTC if a niche channel like Discovery Velocity showed Le Mans in Canada, the same way it's been on Speedvision/Speed/FSR for the last 20 years? And I assume if Discovery Velocity did want to show it, they could apply to the CRTC to alter the conditions of their licence to explicitly allow them to show some racing (like FSR does, or to be like other niche sports channels -- Golf Channel, Fight Network, etc.) if they thought it would be necessary.