I'll stick by my original thought that in todays economy, 539 being rebuilt to operate somewhere just does not seem likely. She'd do well on the SLRG if business was booming.
It is possbile though, that she might be purchased by one or more folks for movement back to the Pacific Northwest and display there.
Too bad about the timing of her coming to the GCR. A few years earlier might have seen a different scenario. She is just a little heavier and more powerful than 4960 with 28" bore cylinders vs. 27" for the former Burlington engine.