You.

PSR's primary benefit is for the stockholders by eliminating unproductive local service and just running through trains. Online customers are welcome only if they can provide and accept complete trains (around 100 cars minimum) at times that fit when the railroad wants to run them. Likewise shortlines, which are treated like trainload customers. The result, if it all works (as we've seen in the railroads that are using it takes a while to work out the bugs), is a low operating ratio and high net profits despite lower numbers of trains and gross revenue, which can be returned to Wall Street as share buybacks (and higher prices == capital gain) and higher dividends.

If you think you've seen all this before ... you have. The Hunter Harrison-directed version was used at CN(+IC), CP, and CSX. Plenty of people learned what he was doing - it's not rocket science. So the expertise is there to do it in nearly any railroad. Railroads that are doing it to themselves (not at the behest of activist investorshedge funds) will probably modify it a bit, and BNSF already does it to a considerable degree.