It was announced as a direct sequence to Breath of the Wild. Why wouldn't it be the same Hyrule?
Majora's Mask was a direct sequel to Ocarina of time and it was not the same world. Wind Waker was a direct sequel to Ocarina of Time as well that took place in the adult timine, and it took place on the great sea. Spirit Tracks was a direct sequel to Phantom Hourglass, which was a direct sequel to Wind Waker, and those all took place in different areas as well.
This would actually be the second direct sequel in Legend of Zelda history (a link between worlds being the first) to do this, so that is a pretty clear indication as to why people would wonder if it would take place in Hyrule or a neighboring region/reality.