The primary flaw in the constitution is that smaller states have disproportionate power (Senate and Electoral College) and will never give up or dilute this power.

Even worse, equal representation for each state in the Senate is literally the only part of the constitution that cannot be amended.

So even with overwhelming popular support there is an absolute barrier to reform.

On the bright side, senatorial races can't be gerrymandered.

On the less bright side, voter suppression and disenfranchisement can fix them a senate race as well as any other.

Senatorial races were gerrymandered in the 19th century when they were converting territories into states. We are stuck with the results of those political battles forever.

The Senate composition can be amended legally. It does require the consent of any state which would lose proportional representation, placing a strong practical hurdle but there is no legal barring of that amendment.