I'm fairly sure that Carrie Henn never acted against outside of her role as Newt. She didn't even bother to come back for A3 because (a) they killed her character off, and when you do see her for a couple brief moments, it's a different actress, and (b) she grew up quite fast between 1986 and 1992. They could bring the character back, but then they'd need to put in an explanation over why she aged so much - or just recast the part.
I think Weaver and Biehn could conceivably be brought back if they toned up a bit, but Henriksen's up there and seems to be split between voice work and film roles as the older gruff authority figure.
You can't really say that "W-Y's time has passed" when Isolation used a similar plot as the original film and had a different spin on things that worked really well (namely, showing that not all W-Y employees were mindlessly corrupt, just that they don't understand what they're up against). A new film could do justice to W-Y if it's handled well.