The decline that some are arguing about was never there to begin with Zelda wasn't a series in decline it maintained the same sales range through out its whole existence it wasn't a franchise in any decline it was a static one in other words a series that just remained with in the same level of appeal. The reason for this isn't anything on any of the directors it's because when you come down to it Zelda as great as they were ultimately were just fancy dungeon crawlers every game hinged on how good the dungeons were to the point the games would end up with clutter in them that literally had no use outside certain dungeons and the world that each game took place was non existent outside of them. Doesn't matter what the formula is this was an issue in the central foundation of the franchise the adventuring parts were merely getting from dungeon a to dungeon b rather than exploring Hyrule.
SS and ALBW began experimenting with ideas that the team wanted to use to break the mold while collecting feed back hence why the former had various notable mechanics and features in it while the latter had a change in structure all of this came together to form the template of what would be BOTW a game that didn't have to be played like a dungeon crawler and made everything outside of them relevant.
To explain what I mean in every Zelda game you have to tackle the dungeons to progress so if you're stuck on one or don't like one in particular it's a case of too bad a common situation was being stuck looking for an obscure switch or chest. BOTW if you're stuck with something it's oh well sod this I'm going to do something else maybe I'll check out that Dragon I saw in the distance or you can still achieve the goal using other ways instead of the intended strategy the rest of the game is not locked to you this means it can now appeal to those who aren't into dungeon crawlers.
This when coupled with BOTW's unique design on interactive sandbox mechanics and physics helped elevate the appeal even more to the point it now even compares with the likes of Mario and is doing the type of numbers R* games tend to do on a single platform. BOTW's sequel needs to be pushed like it's the second coming by Nintendo they should do what R* did with GTA:VC once they found that appeal with the prior game as it can position the franchise now as the first party answer to R* style games.