To me that doesn't make any sense. If it is in the vested interest of a congressman to maintain the convention of gerrymandering then any action to the contrary is equally unlikely. A constitutional amendment is the least likely scenario since it requires majority support of the congress as well the senate and states.

If you cannot expect congress to act in the peoples' interest the only viable solution is through federal court action. In the mean time, since I am in fantasy land (as you call it), I will prefer practical solutions no matter how improbable in the real world over constitutional amendment which is even more imaginary.

Also there is no reason to expect increased seats in congress will have any effect upon gerrymandering and may even make it substantially worse. It certainly won't make law making more efficient.