Renderings are constructive if they generate detailed thinking of all the issues and ideas and problems that need to be worked out. Less so if they are simply pretty artwork for an imaginary case.
Call me pedantic, but whenever a trendy buzzword is slapped on a proposal we are entitled to test whether the proposal fits the title. Does this idea actually deliver better transportation to the surrounding employment area? Does it bring transit from more directions effectively? To me, the LRT routing is awkward and roundabout. If HSR/HFR is not routed through this hub, then the hub doesn't help much. Same with UPE/RER.
It's interesting that GTAA is spinning this as a "transit hub" rather than just a plain airport expansion. The underlying focus seems to be that Pearson is reaching capacity and the best solution is to turn the existing termini into somewhat enlarged "islands", with a new central entry/exit portal. That's sensible, and the transit agenda and the capacity agenda are complementary, so this is all good. But - I'm not seeing the transit improvements yet.
After all, a six-bay sawtooth concrete slab platform with some roofing is a transit "hub" if the right routes meet there. This is a whole lot more money than that.