Your point would be more valid if Colorado had shown more interest for a regional train all the way to New Mexico, but Colorado was and still is dreaming about a high speed train that ran short of New Mexico. At times, Colorado has shown more interest in a high speed train heading west instead of one heading south and north. Without seeing any interest from Colorado and the proposed regional train you espouse, the likely only trains using the tracks north of Santa Fe would have been the Chief. Hello, those same tracks require $200 million in upgrades to keep the Chief at an acceptable speed, and the price of ownership for that corridor in New Mexico was an additional $5 million.
Here's the history of NMDOT on purchasing BNSF right-of-way per the ABQJournal:
In Phase One, the state agreed to pay BNSF $50 million for 51 miles of track between Belen and Bernalillo. Train service on that stretch began in July 2006.
In Phase Two, the state paid another $20 million for track between Bernalillo and Santa Fe. That portion of the Rail Runner service started in late 2008.
The Railrunner total capital costs exceeded $500 million.
Back in 2005, DOT officials defended buying the extra 200 miles of track as vital to the goal of creating the Rail Runner Express. BNSF wouldn't sell the 99 miles of train track needed for the Belen-to-Santa Fe commuter service without the state also pitching in to buy the additional 200 miles between Lamy and the Colorado border for an additional $5 million.
Then NMDOT Secretary Rhonda Faught wrote a column published in the Journal in December 2005, saying: "We didn't go into the deal with idea of purchasing the extra section of track, but it was a necessary part of the deal." "The important point," she wrote, "is that if we were to decide not to purchase the line from Lamy to ... Colorado, the cost would still be $75 million. I strongly believe that it is a good investment for the overall success of the commuter rail project and for New Mexico's future."
http://www.abqjournal.com/news/state/05 ... z2vKKWqHht
Then 2005 NMDOT governor was the Democrat Bill Richardson. Apparently the preliminary decision not to buy the corridor north of Lamy was decided then, although I will grant the final decision wasn't made until 2008 under tHe GOP Governor Martinez.
When BNSF eventually abandons the corridor, NM and CO could apply for some federal rail to trail funds and make a really great bike trail out of this corridor. I would hazard to suggest a bike trail might attract more tourist dollars than the Chief does today.