True -- but you overestimate the cost of adding service to the NCH. And you underestimate the degree to which it would be adding service on existing routes. First of all, it would share all facilities from Seattle (or Portland, whichever is chosen) to Sandpoint ID and from Minneapolis/St Paul to Chicago. And also at Fargo. (And depending on the chosen Minnesota route, also from Fargo to Minneapolis/St Paul.)The point is that the cost of "planet alignment" for a North Coast Hiawatha would be much higher than operating the Sunset and Cardinal daily. The whole Amtrak long distance system is fragile. It's much more cost effective to add service on existing routes than to spend a billion on a new one which needs a lot of station and mechanical facilities.
Most of the stations on the line still exist, and basically require the usual "patch up the crumbling platform and add a ramp". Some would require "pour a new platform". Very few would be staffed. Station buildings are generally the responsibility of the cities these days anyway; many still exist and some would probably be revived, but it's not a necessary component of the project (see: Texarkana).
As far as I can tell there would be zero new mechanical facilities needed. Three or four new crewbases with the Willmar route, one fewer if the existing St Cloud route is used.
A number of new stations: the maximal list west of St Paul and east of Sandpoint would be
Minneapolis (at existing Northstar station)
Fargo (at existing Amtrak station)
This is probably overkill. Ignoring the already-existing stations, a more reasonable startup list would be:
Bismarck OR Mandan (they're in the same metro area, very close)
This many stations should be $24-$60 million. Peanuts. The track & signal upgrades would swamp this.
The three Minnesota stations could be skipped in favor of the existing route via St Cloud if Minnesota support was lacking or CP didn't play ball.
I firmly believe that it would be critical to schedule the NCH in a different timeslot from the Empire Builder from Chicago to Fargo and Sandpoint to Seattle (or Portland, whichever is chosen) in order to create a second frequency. This would be a critical component of the plan.
This would be the Silver Star/Silver Meteor of the North. That's the idea.
Frankly, I think it's going to be easier to get the "new to Amtrak" track upgraded and agreement to run one train a day on it -- than it will be to get host railroad agreement on the parts where this will be the second daily Amtrak train. I expect the demands for double and triple tracking from Chicago to Fargo to be high, and likewise from Sandpoint to Seattle (or Portland) -- while I expect the plain track from Fargo to Sandpoint via Helena to be much less contentious. Why? Less freight traffic on the latter.