It does, in both a positive and negative manner. In the positive sense, it means that the freight railroads will now upgrade tracks and signaling, making Amtrak trains run faster and more reliably. In the negative sense, it means that there will also be more freights on the tracks,
meaning more delays due to more freight trains on the tracks. Which trend will prevail, I couldn't say. My bet is, however, in the short term things will get worse as the freights try to shove more trains on the tracks; once capacity is reached, then they'll try to upgrade and things will improve. Note, however, that track upgrades will make some new Amtrak routes available that weren't earlier.
Overall, however, I think this will be best for Amtrak, as more and more interest goes back over to rail, and lines improve. This can't help but improve the general Amtrak