I feel more or less isolated in thinking I don't miss Minsc and Boo nor I wish for their comeback one single bit.
No, I have had quite enough of M&B. And rather more than enough of a certain unmentionable gnome. I'm actually not certain I would want any of the BG1/2 companions as BG3 companions - although I might reconsider after experiencing what BG3 does have to offer
I would expect some of the original companions to appear through tavern stories, or as incidental characters, maybe even as adversaries. The fact we have a Cleric of Shar as an origin companion might signal a story thread including Viconia DeVir, for example.