Can you prove otherwise? It's a over 30 years old game, and people 80% of people who own Switch in USA are 34 or less years old:
It's unfortunate I don't have a newer source, these numbers are now 26 months outdated, But they came out when BOTW was around for 1 year already
Of course each game has it own sales demographics, but I don't see why Zelda buyers would be considerably older than average
Plus, even if you're taking into account the newer players (people younger than 35 years) that played the original Zelda in some pirate emulator, virtual console whatsoever how can you make sure these people that played the first Zelda find this specific game design any better than the subsequent Zelda games such as ALTTP, Ocarina of Time, Wind Waker, etc and indeed prefer the first Zelda game to any other of Zelda games?
Seems like the argument you want to sustain is the first Zelda game was loved, they changed the direction due to some console limitations and it was successful for a while (Ocarina of Time) and then people get bored of the OoT formula and wanted Zelda to back to their origins. But honestly, this "return of origins helped to increase sales" point doesn't hold any steam.
I think I agree with what you said about Aonuma's formula making Zelda losing potential gamers. It's true, any game have it's own target demographic and not all kinds of games will meet the same public reception. What I disagree is that backing to their origins is what changed that scenario. IMO, what make BOTW stand out was the incorporation of modern game design elements into its gameplay
People who were Zelda fans loved Zelda they knew, and the Zelda they knew is (mostly) the Zelda of Ocarina of Time onwards. OoT was the 4th best N64 seller for a reason, and it rivaled Mario 64 and Mario Kart 64, so it's quite meaningful. Ocarina of Time for 3DS sold over 6 million copies and it was a storming remaster, Majora's Mask for 3DS sold 3 million copies about the same as the original game. The Wind Waker 2.5 million in a flop system
My only conclusion of this is the "potential gamers" who jumped into BOTW aren't Original Zelda fans/players, they are brand new players who discovered some years ago that open world and exploration games are great and then give BOTW a try because of the awesome world of mouth and reviews. Or even better, it was their first open-world game and again they give it a try because of the already mentioned great world of mouth/reviews.
First, is your argument not mine. You can't demonstrate your argument: young and mid 30 people don't play Legend of Zelda. It no elucidates. So it's only a theory, a theory because it doesn't have numbers, studies, research, history can prove it.
I demonstrate with numbers, NES mini sells well(scalper anywhere can prove this). I demonstrate with tendency: when a game based on this root, likewise Mario Kart tends to sell well, plus expansion and penetration, sells better than his predecessor. Nintendo games tend to go well when based on the roots. I demonstrate with a counterpoint: Zelda is away from his roots, with Aonuma makes trains and try to take Link sword off, etc. Aonuma never understands Zelda roots, because of this, the franchise is in decline, even with the market expansion and the penetration of new markets made by Nintendo, she does not transform Zelda in success, otherwise, Skyward Sword sells only 4 million, Aonuma rip overworld in Zelda completely and the sales fall down a cliff ( reflecting the considerable increase in sales of other games, such as Mario Kart, Smash, 3d Mario). I demonstrate with games history: Nes was a phenomenon, even though it sold only 60 million, because of Famiclones ( more than 350 individual models) and piracy cartridges. NES market was much bigger than the official distribution.
And BotW back to origins because the original Zelda is that: arcade games plus PC games. The first and second Zelda and BoTW have the same feature: a fusion arcade game( Nintendo origins) with the modern PC gamer in the moment ( Ultima, Wilzardly in first Zelda and second Zelda. Minecraft, Terraria and Skyrim for BotW). Back to origins brings ex gamers, then ex-gamers bring new gamers. That's the expand the market. And the demo of BoTW based in The Legend of Zelda brings the roots in evidence.