Not only that, but they built an impressive serpentine accessibility ramp for people who cannot use the stairs. I'm pretty confident these stairs are not temporary. There's nothing wrong with them, as long as the moat glass covers are coming, as planned.
The stairs are temporary, the ramp is not.
The new final ground level at Union Station is complicated. The central and west moat will be at the same height it is now, and the ramp will serve that in perpetuity.
The stairs, however, are going to go eventually.
That will happen in phases. Once the new stairs open, they can close and demolish the current ones and start another dig-down.
The next dig-down will get people up from subway concourse level up to central/west moat level with west-facing stairs. They'll be walking that way as of this Fall when the York Street GO Concourse opens and the Bay Street GO Concourse closes.
Once the Bay GO Concourse closes, they'll demolish then start a dig-down there. That dig-down will take the GO Concourse area down to the same level as the subway concourse, and the same level as the new mall sections currently being built behind the scenes at the station. That means stairs facing south from the subway concourse will no longer be needed, and that there will be a huge fully accessible area down there all at the same level.
Here's a plan on which you should be able to find all the components I'm talking about. For example, the permanent stairs from the subway concourse to the west/centre moat area can be seen below the purple arrow just to the right of "Front Street Centre Moat", and the dug-down current GO Bay Concourse will become the Bay Street Promenade (more new mall space). If you look around the plan, you'll see the other stairs that will go in to connect the dug-down areas to the areas which will remain at the current lower level.
Hope that clears it up, but quiz me if it doesn't!
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