You need 2/3rds majority to pass the constitutional amendment required to make this happen, so as long as Republicans exist this isn't going to ever be the case. It means they'll never win another election.
Not just that, you then need 3/4 of states to sign off on an amendment before it takes effect. More than 1/4 of states benefit from the electoral college, which makes it a hard sell.
There's also that interstate compact (which if it ever takes effect will be challenged in court on grounds that interstate compacts are supposed to be approved by Congress), which is also highly unlikely to take effect for the same reason - there aren't 270 electoral votes worth of states that are either big enough that the electoral college hurts them or willing to hitch themselves so going along with whatever the two or three largest states want.