The Belen station was purpose built for the NM Railrunner. At least when I lived near by in Los Lunas 5 years ago, the track was a new spur that deadends on the South end. The old ATSF station is on the other side of the yard. In fact, if memory serves, the Railrunner can't even cross over to the Westbound Dailies sub from it's station.
Back to the ATSF station. It is a beautiful, unrestored but in good condition Harvey House. A model railroad club and a quilting group use the facility. There are some museum artifacts there. I went upstairs while an AA meeting was going on downstairs and the rooms were as they were 60 years ago. Time doesn't decay much in NM.
I don't remember much about the platform so can't say if it could physically handle an Amtrak train set. There are some benches for watching the trains enter the main line after a crew change and a fueling stop.
Any Railfan could spend hours there.
That bring said, the station could handle passenger service, but parking is all but nil. A transfer to the NM Railrunner would require a bus to get you up and over the yard. Not a practical junction to take the NM Railrunner to points South of ABQ.
I've seen the wye, and it's a painful backup move. Not Ft Worth Tower 55 bad, but still a pain. I believe the wye is in the midst of several gas/oil storage tanks.
Frankly, I would live to see the SWC serve Amarillo, but only if it could still come through Trinidad. I hope they restore this track to it's full glory.
Oh, btw, Belen has quite a quaint rail fan friendly coffee shop on the other side of the Railrunner parking lot.