Undoubtedly, the Larian Studios version of Baldur's Gate 3 will be considered as the "real" Baldur's Gate 3, because it actually went past the project stage. But the 20-year gap between BG2 and BG3 makes you think what actually *is* a sequel. Some of the people currently working on BG3 weren't even born when the original Baldur's Gate came out. And with a completely different development studio behind it, Baldur's Gate 3 frequently resembles Divinity Original Sin 1or 2 more than it resembles Baldur's Gate 1. Fire or acid surfaces on the ground? Not really a Baldur's Gate feature!

Baldur's Gate more or less spawned its own genre, with games like Planescape: Torment, Tyranny, Pathfinder: Kingmaker, the Pillar's of Eternity series, the Divinity Original Sin series all drawing inspiration from the isometric style of Baldur's Gate. Other than having a D&D license, and thus using the same names of spells, Baldur's Gate 3 is just yet another game inspired by the original. There is no link to the story or characters of the original, it is just another game resembling it. Baldur's Gate 3 could just as well have carried another name. The only significance of the name is that it indicates that the game has an official license from the makers of D&D.

In a way "the next game by the people who brought you game X" is a better indication than "sequel of game X". Sequels indicate an aspiration, and are a marketing tool. But the gaming industry is full of sequels which fell far short of the original, whether it was the same studio or a different studio that made them. With RPGs the originals frequently were turn-based and had fixed camera angles due to technological limits at the time. And then some sequel years later is suddenly a first-person real-time action RPG, which plays totally different.

I think the lesson here is that you shouldn't buy a sequel just because you loved the original. Approach the new game as if it had a new name. Read the reviews, watch some gameplay, and decide whether you like the *new* style.