Yes, the whole "3" part is suspect. I hope it's simply to cash in on the name, and not to imply some kind of continuation. Since Bhaal has indeed returned in 5E, they might do something like that, like you are a new batch of Bhaalspawn or you are his agent (that's gonna be cool). I know we won't be able to avoid Minsc, so I hope it's a cameo or something, and not a full-fledged companion.
Reminds me of when Eidos Montreal were developing their crappy Thief game back in 2013, and there were some people on the forum who were upset it wasn't a real sequel with the same character as the original trilogy but instead more of a reimagining. They thought that made the game a "cash grab". And I was like, "Are you guys nuts? You don't want them touching the original setting, trust me!"
It seems obvious in retrospect but there really were people who were upset about this. Yes, when you make a sequel this many years apart from the originals, when the developers are entirely different people, it is better for them to be playing in a different sandbox. If only so you can safely file the game away if it turns out bad.