An interesting idea, as it implies that a number of hands out from the win the player has to start "playing them", because you can only play one card a turn... but I'm not sure it will enhance game play.
While you talk about fluke wins, right now a key part of the game for experienced players is to be analyzing what someone is doing/not doing with cards (and their position) to keep track of how they could win, so that you make tactical decisions on whether to make moves earlier or later in the game.
If someone catches you off guard because they have hidden VPs, or take the road and largest army in one round, or port master if playing that scenario, that isn't a design flaw or a fluke - that is a player not properly reading the board and their opponents out playing them.
This is a game of strategy, and anything you do in the rules of gameplay to force people to reveal themselves or impede a winning move ruins the opportunity to develop players into people who can read the board and possibilities well, and for advanced players to outplay less experienced players.
