Twilight Princess will probably plateau at 500,000 in Japan. Ocarina of Time in just a bit over 5 weeks sold over 1 million copies. In it's lifespan, OoT sold 1.5M in Japan...or about a million more than TP. TP sold half as many copies as OoT in the first week of release.
The Wind Waker broke 900,000 copies so far, still well short of OoT. In the first week of release, OoT sold over 100,000 more copies.
It should be noted OoT stayed in 100,000 range until about it's 8th week, when it dropped 50% in sales after the holiday rush ended. TWW and TP both came close to OoT's weekly sales in week's 8 and beyond.
Again, this is only Japan data.
I mean, Zelda had sold well in Japan at points, but it is not the mega blockbuster that is Dragon Quest, Final Fantasy or Pokemon. Zelda is clearly a Western franchise now, and I doubt anything Nintendo does short of selling out to be more like Final Fantasy will make its sales be anywhere near the giants in Japan.