If GTAV is the standard for "commercially successful game" - practically everything else is a commercial failure.

A huge chunk of GTAV's sales are the PS4/X1/PC version. Are you going to tell me those sales don't count? Because those are remakes too.

Those hit 10 million due to remakes, not indvidual buyers. heyre around 8 million individually probably.  Similar games in similar genres have sold far more - Witcher 3, Skyrim, Fallout, RDR and Far Cry. Zelda BOTW is an open world game similar to those (perhaps less Far cry) and I doubt it will outsell them. 

You should hit 10 million if youre mass market. A lot of games do nowadays. Square doesnt even smile when their games hit 5-6 million, they call them flops basically.

Dude...wat are you on about? 

First, 4 million is not an indie number.  That's a massive runaway success for an indie.  The overwhelming majority of indie games can only dream of hitting 1 million sales.  95% of indies would KILL to sell 4 mil.  Shoot they would kill to sell ONE million. 

Second, Skyward Sword failed to reach 4 million due to 1) launching at the tail end of the Wii's lifecycle, 2) launching AFTER the successor system was announced, and 3) having its production cutoff far earlier than a typical Zelda game would have.  That last bit made it quite literally impossible for the game to reach its full sales potential. 

Third, just for the record, Twilight Princess sold nearly 9 million.  Just fyi

Fourth, all those games you mentioned are *multiplatform*, Zelda is exclusive.  Only a small handful of exclusive IP have ever been capable of 10 million once, much less consistently.  Only one Halo sold over 10 million.  No Uncharted game has yet to sell 10 million (in fact, no Naughty Dog game has, iirc).  Are those niche franchises? 

Fifth, 10 million being the standard for mainstream is absurd.  Consistently selling over 4 million and often selling significantly more is not "niche".  And as for your SE example, that has nothing to do with mainstream vs niche, that has to do with budget vs revenue. Square Enix is notorious for their overspending and extravagant budgets, that's why they NEED their games to sell as many as they do.  Have a high enough budget and even 10 million won't do you any good. 

In short, Zelda is not niche, you don't seem to understand the meaning of the term, stop trying to sell it cause the argument isn't going to fly.  Because the argument is nonsense.

Persona had a high aggregate and reception too. Arrogant to say "only Zelda." 

Nothing to do with preference. 

Yup, name value helps tremendously. 

Saying that any series that hasn't passed 10 million in a single entry is "niche" is ridiculous, 99+% of franchises never cross that mark.

Even if we exclude remasters/ports, Zelda has already passed the 7 million mark twice, and Breath of the Wild is going to pass 10 million anyway, it's over a third of the way there as of its first month.

Nier, that I don't think will be nominated. But P5 still has a chance.

Most people do not share your defintion of "niche".

Persona 5 is mine but zelda will probably win.