Honestly unless the people in here defend abolishing the states and ruling all of the US as a single unitary state like say France, they should defend the existence of the Senate.
One of the biggest aspects of federalism is the existance of a second chamber, that is represented in a 1 state = 1 vote basis, to counteract the lower chamber that is 1 person = 1 vote (at least in theory).
Since I am a big fan of federal states for the most part, and there is no real reason to turn the US into a unitary state, I would keep the current senate structure for the most part.
As for in terms of legality, while the Senate can't be abolished it could still be rendered powerless by making it into a chamber that does not matter and can be overridden by the House like the British House of Lords (or the Spanish Senate for that matter).
That doesn't make sense. If the Senate is "rendered powerless" it can't "counteract" the House.
