As long as there are people who allocate billions with a sign of the pen, with zero personal responsibility and skin in the game, there will be whole industries dedicated to swaying their hand.
To put it another way, I still put a lock on my door even though lockpicks exist. I still use passwords on my accounts even though people could guess or brute force them.
Don't trivialize things to uselessness
For example, we could behead people convicted of corrupting or being corrupted. That would be a significant deterrent.
This has historically done nothing for corruption and everything for one-party rule.
We also need law establishing mandatory retirement for Congressmen and judges, including justices, and a system where each President appoints (with Senate consent) one and only one justice to SCOTUS. Finally, yes, pass McCain-Feingold, pass a SCOTUS ethics bill and make corruption charges easier to bring.
This is my only significant disagreement with you. This should be two justices:
1) An 18-year (9*2) term is more compatible with age limits than a 36-year term
2) Each Senate class gets to participate in the appointment of one justice.
I like No. 1.
No. 2 seems overcomplicated compared with staggering retirements in the way Art. 1 § 3 cl. 2 staggers the Senate. The Senate is also more diverse than the Presidency; limiting the latter would check against some dirty tricks.
It's also untrue to suggest that any intervention will necessarily create a worse outcome than the status quo.