Unfortunately it lost legitimacy already
As long as people participate in the two party cicrle jerk, they will continue to rule as they see fit. Just because you and I mock them online, doesn’t reduce their legitimacy.
If we have a situation where D 25 R 25 third parties combined 50. That’s the type of loss of legitimacy I am talking about.
The only people stupid enough to follow your bad plan are on the left, the right is a cult. It will be D10 R49 and the stupid people vote combined across several candidates never breaking double digits 41. Great plan…
Then the next election will be D75 R25…but the king will invalidate the clearly rigged elections, because look at the last one, must be a Dem Hacking ring changing the votes! R still wins. Supreme Court shoots down appeals.