OoT 3Ds went to sell more through time as 3Ds sales soared, unlike the WiiU's. 1.6Million is pretty good for any remaster, specially with such a low user base. As for the price Wind Waker HD came out at full price, 36 pounds or 59.99 Euros here in Europe. And i saw people in the US complaining...
1.6 millions for a re-release at full price its absolutely impressive. I expect TP to do the same, the Zelda fanbase while not as broad as it used to be its a returning costumer. Likely people who bought WW HD will buy TP too.