That argument is a bit of a reach as the 3DS game is a remake, TP was a multiplatform release so it makes sense counting them together. If you're going by your current logic WWHD's sales should be added to WW making it the 4th highest selling Zelda game at 6.1m and TPHD's sales when released will be added to TP's sales.

Well then once we add in Twilight Princess HD sales, I'm sure it will take the lead again.

Adventure of Link, Link to the Past, Link's Awakening, Majora's Mask, Oracle of Ages/Seasons, Wind Waker, Phantom Hourglass, Spirit Tracks, Skyward Sword and soon to be Link Between Worlds have sold in the 3-5 million range and averaging about 4 million.

3 exceptions (Legend of Zelda, Ocarina of Time, Twilight Princess) have sold higher averaging about 7 million, while 3 exceptions (Four Swords Adventures, Minish Cap, Triforce Heroes) have/will sell less averaging around 1 million.

This is not including ports/remakes.

Unlikely.

TP currently stands at 8.8 million, Ocarina at 11.4 million.

TPHD would have to sell over 2.6 million copies. No way that is happening.

Wind Waker HD is at 1.5m, Twilight Princess HD will most likely match or exceed, let's say 2 million putting it at 10.8m, 5% difference and pretty much a statistical tie.

But for the rest of my post, it shows Zelda really isn't in a decline, more like the series goes through its ups and downs while staying around 4 million the majority of the time.

A difference of 600,000 units is not a tie, and that's a very optimistic prediction for TPHD.

Ups and downs yes, but the current downward trend has been going for a decade on both console and handheld entries. Together with the steep decline in Nintendo's hardware base, thus limiting the user base Zelda U is available to, I see little reason to believe Zelda U will have sales anywhere near Ocarina or TP.

I don't see how it's a trend

Legend of Zelda-6.5m, Adventure of Link-4.4m, Link to the Past-4.6m, Ocarina of Time-7.6m, Majora's Mask-3.4m, Wind Waker-4.6m, Twilight Princess-7.2m, Skyward Sword-4.0m. Down, up, up, down, up, up, down. Based on that trend Zelda 2016 will sell higher than Skyward Sword and the following one will sell higher than Zelda 2016.

Links Awakening-3.8m, Oracle of Ages/Seasons-3.8, Minish Cap-1.4m, Phantom Hourglass-5.1m, Spirit Tracks-3.3m, Link Between Worlds-2.7m. Tie, down, up, down, down (perhaps tie when done).

Basically the typical console Zelda sells 4+ million while the typical handheld Zelda sells 3+ million, with a few exceptions each.

Look, surprises make us keep anticipating for the game. That's cool.

It's annoying for games(especially pokemon) when people get the game 1-2 months before it's even released and reveal every bit of detail for the game.

I don't know about everyone else, but I prefer 8-10+ years ago when all we can do is wait and get hype.

Both charts end on a down, (a very protracted down) and the diminishing of Nintendo's hardware base further restricts the amount of gamers Zelda U will be available to.

That doesn't make it a trend, if both were seeing consecutive downs than u would have a case but console has one down and while handheld currently has 2 downs it will likely be a tie in the end or such a small decrease that it's really not worth mentioning.

The last console Zelda is at 4m, Wii U currently has 5 games over 4m, Zelda U selling over 4m isn't out of the question if it remains exclusive but I personally see it being a dual release like Twilight Princess was which makes me believe it will without a doubt sell over 4m.

That's what a trend is, change over time. On both consoles and handhelds, Zelda's recent entries have sold less than they did back in 2006-2007.

If Zelda U does manage to outsell Skyward Sword, (which is certainly not impossible) it will still be a far cry from the popularity the series enjoyed with Ocarina, TP, or the original game.