That won't work Lerticus. It's just the same problem as Britain and Canada (among others) by that point.
You shouldn't try to make an argument that something should not happen while citing as evidence places that function better than your own system.
Could an amendment to merge the chambers even theoretically pass? Article V stipulates that states shall have equal suffrage in the Senate and that no amendment to change this can be passed.
Well, I suppose theoretically it could if we radically re-interpret what 'equal suffrage' means, in a way that makes sense in a modern context but would send constitutional originalists frothing at the mouth.
As with everything in dealing with that archaic document, it has been repeatedly debated, and there is no clear consensus.
For example, there is no protections within Article V that stipulate that it cannot itself be amended. With that being the case, some people can argue that there is an implication that it is protected, but at the same time there are enough people who argue that the Constitution must be read literally (hello, 2nd Amendment) where the absence of self-protection should be interpreted as the Founding Fathers' desire to allow the Constitution to be completely modified as needed (and there would certainly be other documents by those individuals that would back up this intent).
So there are technically 3 different ways that Senate merger can happen.
- Pass an amendment to Article V, removing the protection clause. Then there is nothing preventing another amendment from going through.
- Article I's vesting clause can be amended - which provides the declaration that there be two separate chambers - to one chamber. This does not necessarily mean an abolishment of the Senate as a group of representatives, only their position as a second house. In such an amendment the states can still elect or appoint Senators as representatives of the state rather than of an individual electoral district. End result is only one mixed-representation shitshow chamber instead of two.
- If somehow a Constitutional Convention were opened the old Constitution is toilet paper. A new document is drafted, the protections no longer exist, and the only way that those protections get extended is if they are also written into the new document.
Further, consensus is that "equal suffrage" means only that the states may all have an equal number of representatives. This number can be changed from 2 per state to 1, 3, 741, or theoretically to none if the articles on the composition of the legislative branch are altered so that the duties are handled by the other chamber. You could amend the powers of the Senate to be purely ceremonial (by Grabthar's hammer what a savings), or could amend the role of Senators to be filled by puppies and kittens. The Article V protection is actually quite weak since it only guarantees equal representation while not preventing changes to absolute everything else about the Senate.
All that being said, I already acknowledged that any changes are already moot. There is almost no way that another amendment will ever get passed with the way that partisanship has taken hold, a Constitutional Convention even less likely, and the entire system is stuck in a stasis where even discussion of change is an unspeakable horror. End result is that the Senate effectively can never be fixed, so it is up to the states to fix the House of Representatives.