Plus the land along the QEW in Oakville and Burlington is nearly maxed out, or would require redevelopment of existing buildings.
I don't know what the plans are for the greenfield properties adjacent to the 401 in Milton but I assume the stretch from James Snow to the 407 interchange will be much like the lands west and east of it. That's one of the last "open" areas on the west side of the GTA.
Hamilton's proximity to the borders (especially with New York state) is a huge plus as well. Hopefully we see more redevelopment of empty former industrial lots, like that
new business park on Victoria... some will require remediation but as other more easily developed land is gobbled up those blocks become more attractive and economically viable.