I don’t see how the Canadian government can write regulations that would force U.S. owners to build seaworthy U.S. flag vessels.
What’s stopping any vessel that doesn’t meet Canadian requirements from just staying off-shore?
The second problem what are the chances the Canadians would write and enforce regulations (whatever they are) in practice? Assuming they figure out a way to do it.
I’d say the chance of this situation being fixed with Canadian regs is practically speaking about zero.