Also, a naïve question about km numbers on exit markers:
Suppose that 417's extended to SSM, but that Transcanada Freeway follows 11 NW of North Bay and then 17 NW of Shabaqua Corners.
So through North Bay, the exits will be marked according to the km's of 417, which is increasing from Quebec border. For the purpose of this question, suppose that Highway 11 Cochrane-bound branches off 417 at km marker 512.
Now, how should the km numbers on the Transcanada Freeway be signed? Should they be increasing from 512, should they be reset and start from 1, should they carry over the km numbers from Highway 11, or should they now start from 1 at the Manitoba border? (Also, should this freeway be renumbered Highway 1 with Maple-leaf shield just like how it's done in Western Canada?

)
Ps: This is one of the reasons as to why I think twinning should be done on 17 instead. It isn't a good one though.
Edit: I forgot to mention another option: We can alternatively keep the km numbers of Highway 11, but once the freeway reaches Nipigon, they will be marked in increasing order from 1510 (distance betweenness Nipigon and Québec border via 17/417)
as if twinning is done on 17 instead. Imagine having a monument for km marker 2000 near Vermillion Bay. If done right, that can well boost the economy of the small town.

Unfortunately a monument for km marker 1000 at 11/631 near Ameson will be a much harder sell...