I think it's the opposite, it will be replaced around its 5th anniversary. DS got 6 years but that's an anomaly because it sold far, far more.
Beyond that, Nintendo has thrown just about every franchise at the 3DS they can already by the time the end of this year rolls around.
The huge drop in sales is because of smartphones/tablets, leaving the system out to dry artificially is not going to help Nintendo it's just going to ruin any momentum they would have otherwise.









