> If the freeway were to go to Vaughan, I'd terminate somewhere north of
the 400 Services Centre between the King Road and (almost open) Teston
Road > Interchanges. Somewhere like Kirby Sideroad or King/Vaughan Rd.
Then relocate one of the service centres.

I agree that somewhere in the King Road or Kirby Sideroad area would be
a good place to meet up with the 400, but I wonder if it would be better
to swing north of Bolton and skirt the south side of Orangeville and
then follow Highway 24 to Guelph, or squeeze south of Bolton and serve
the north side of Brampton along with Georgetown and Acton instead and
then follow Highway 7 to Guelph.

There would also need to be an additional Peel/Halton north/south
connector, be it a freeway that extends north from the 407/401
interchange to Georgetown, or a four-lane Neyagawa Blvd/James Snow
Parkway that extends past Milton to the new freeway in the area of
Acton. The connector doesn't necessarily need to be a freeway, but it
would need to be a high-speed four-lane road. One would also assume
that Highway 6 would be at the very least RIROized between Clappison's
Corners and Freelton, and a new freeway from Freelton to meet up with
what would be a freewayized Hanlon into Guelph.