A while back, the BNSF elected to run their transcon route through Texas and Oklahoma into Emporia, Kansas. This bypasses the former Santa Fe route which went through Newton (Wichita), Hutchinson, Dodge City, Garden City, Trinidad, etc. The only thing running on this track is Amtrak's Southwest Chief. The Chief has recently been slowed down on this leg.
If BNSF allows Amtrak to run the Chief on its new transcon, will travel time for the Chief be reduced? Have seen the roadbed and it's in good shape. Those Kansas Cities would loose Amtrak service, but when you look at the times the trains comes in (the middle of the night), doubt it would have much affect on ridership.
Santa Fe actually made the decision to reroute the "Transcon" long before the ATSF-BN merger; the route through Texas and Oklahoma via the Belen Cutoff has
always been the primary freight route between L.A. and Chicago since its completion just as the route via Raton Pass had been the Santa Fe's principal L.A.-Chicago passenger route until it transferred the remaining passenger service to Amtrak in 1972.
To answer your question, it really depends on how closely BNSF works with Amtrak to coordinate their respective operating schedules. The entire Transcon route has been double-tracked and converted to CTC signalling except for the Abo Canyon segment, and that is being converted over at this moment (all that's left is finishing the roadbed on the new alignment and laying down track and ballast, along with getting the new signals in place), so there's no reason why the
Chief's schedules couldn't be speeded up. You're also right about ridership; there's not too many folks who get on or off between Albuquerque and Newton, Kansas (the two points where the
Chief would deviate from or rejoin the old route) and most of those could use Amtrak's Thruway Bus connections to connect with the
Chief or even the
California Zephyr. For that matter, there's probably enough potential ridership in Amarillo and along the Panhandle Sub to make up for what might be lost in Colorado and Kansas if the
Southwest Chief is rerouted to the Transcon. And that rerouting could happen fairly soon, now that New Mexico's new Governor has made clear that she's not interested in having the state buy the rest of the Raton Pass route north of Lamy; BNSF itself had already had proposed rerouting the
Chief back before the previous administration had expressed interest in buying the line, so it's possible that BNSF might still be willing to do so.