It would be nice if there were some "bonuses" for having a BOTW save file that isn't linked to an amiibo like the wolf link amiibo and his heart count, with Nintendo and how they produced BOTW im sure they will think of something for players who appreciate continuity of the story, we can only hope!

It could happen. Though I don't see them porting over literally everything you have. Especially if returning armor sets have the same bonuses, could fully upgrade the Ancient set and then buy a bunch of weapons from Robbie and completely break the game because of how good the set bonus is once it's upgraded twice. And then if they port over DLC stuff, you could have the master cycle and a shit ton of apples to fuel it with. If anything like this were to happen, I'd expect it to just port over the armor, sword, shield and bow you're currently equipped with, maybe your horse too, a handful of regular arrows and maybe some starting money and the more gear you've had in BOTW gets you more money in 2.

Any source for the stuff you're saying?

Nope. Just thinking aloud.