No Waterloo is not and will not call itself a part of greater Toronto. It's like saying Baltimore is a part of DC (just a little bit closer), or like saying Philadelphia is a part of New York City (just a little bit farther).

Kitchener-Waterloo is a distinct town, and is a part of the original Canadian "Tech Triangle" - with the demise of RIM/Blackberry, it's lost the lustre but there's no way anyone can take seriously bundling Waterloo into the Greater Toronto Area.

Bad example, Baltimore and DC are usually considered part of the same metro area.

Waterloo is over 100km away from Toronto

Which is similar to the distance between Santa Clara and the Golden Gate Bridge, for what it's worth.

Does driving between Santa Clara to the Golden Gate Bridge include farmland in the middle?

If Waterloo is part of Toronto, you may as well count in Hamilton, Oakville, and Milton as well. Hell, throw in Niagara Falls.

Those cities are actually part of a geographic region called the Golden Horseshoe Area, which is more comparable to Census Statistical Areas in the US (like the SF Bay Area, Baltimore-Washington Area, and Chicagoland).

It's called the "Greater Toronto Area" for a reason.