I don't think the engine house is new, unless it was moved or reconstructed from an older one. When I walked inside, the building itself looked reasonably old. But clearly a new plywood front has been added, including some new concrete floor and foundation work in the front.
While riding between Carcross and Bennett, there was a lot of evidence of new work on the line. Some of it clearly had been done this Spring (one bridge had what looked like a brand new deck), and did not date back to the original reopening of the line several days ago. There is a HUGE pile of what looks like new 115 lb. rail at Carcross (I did not check it closely).
The line from Carcross to Whitehorse still looks passable, but does not look as if it has had any activity since the pipe salvage trains of a few years ago. I wonder if they patrol it on any kind of regular basis.