You forgot one very important check on the Supreme Court. According to Article 3, Section 2, Clause 2: "In all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party, the supreme Court shall have original Jurisdiction. In all the other Cases before mentioned, the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make." Therefore, Congress can remove entire classes of cases from the appellate jurisdiction of the Supreme Court.
Wow. I never noticed that before.
Yeah, an if Congress tries it, expect a goodly segment of SCOTUS to say this violates the all-malleable Equal Protection amendment.