No. Given the number of states we have and the way population is distributed among them, there's absolutely no way of realistically going to proportional representation without either eliminating the allocation of Representatives to States and thus weakening the Federal system or going to an unwieldy House with more than triple its current size.
Shouldn't larger states (e.g. California) be allowed to try PR on the state level? I'd prefer that to our atrocious top-two system, anachronistic Supreme Court decisions be damned.
I'd have no objection to it. Indeed, the only thing standing in the way is not the Supreme Court, but Congress (and the state legislatures of course).
Yes, through a MMP system. And enlarge it substantially. Abolish the Senate.
So basically eliminate all pretense at having a Federal system of governance?
Theoretically, why would that necessarily be the case?
If you eliminate the link with States, then the National government would have no reason to consider the State governments at all. Indeed, I would favor replacing the 17th amendment with one that restored the election of Senators to the State governments, but in exchange would limit the powers of the Senate unless legislation impacted the State governments in some direct form.