People often say stuff like "the founders would have changed their mind if they knew just how concentrated the population would end up [wrt representation]", but they don't propose anything specific or constructive (short of federal-state litigation, secession or another civil war). How about a (neutral) commission to reapportion State boundaries every 10 years based on Census results (with some population formula between not-quite-linear and wildly disproportionate)? Or else, to periodically reapportion state counts of Senators to total 100. (Obviously these couldn't get ratified these days, but they just might have in the 1790s). If not, what's your specific suggestion?

Another thing people aren't currently discussing much is how badly break down if/when the Supreme Court gets captured by a dominant group that is both ideological and not independent. Look at how high the stakes will be for nominating the eventual replacement to Justice Clarence Thomas/Sotomayor/etc.

And of course the terrible Citizens Utd ruling muddies every consideration of representation.

And then there's also the parallel discussion of the Senate filbuster rule, remember though that if there was no filibuster, Citizens Utd would allow unlimited dark money to influence every vote, specifically all the action would focus on the Senators in the middle, think Joe Lieberman, Olympia Snowe, Susan Collins, Manchin, Sinema. Seems near-impossible to reconstruct democracy under these constraints. (Look at the recent Senate stealth attack in the shutdown bill by lobbyists for newly-legalized CBD to try to ban Hemp).