I recall reading somewhere the argument that Congress cannot eliminate a court because it would result in a judge losing his job, which would be, in effect, a "diminishment" of their compensation, which Article III Section 1 expressly prohibits. On the other hand, Article III Section 1 also says "during their continuance in office," so one could counter by saying that eliminating the Court discontinues their service, making eliminating their compensation Constitutional.
Anyway, an argument only lawyers and judges could love.
-PJ
What happens to pending cases and trials in progress if a court is eliminated?