Interesting points. Cat's Cradle, I'm with you in hoping that Sigourney Weaver's involvement is a good sign. Admittedly, she has signed onto projects in the past that, personally, I haven't found all that inspiring but perhaps, at this point in her career with financial concerns surely a non-issue, she might be interested in this project for its own merits.
And, Remedy, giving some thought to that concept art, I think it might be the main reason for much of the excitement that's been generated about the film so far. Yes, the characters appear older (and they should) and Hicks is physically scarred from the acid burns he suffered at the end of Aliens but the look is still very reminiscent of that movie, even down to the clothing and the color palette (James Cameron always has liked blue hues). In many ways, the concept art works because of the nostalgia so many of us feel for the original two movies. It's a bit like the trailer for the new Star Wars movie actually. It seems many people think that movie will be the greatest thing ever and, having seen the trailer myself, it's hard to see what the excitement is about beyond some recognizable images. Show people an X-Wing, show them someone in stormtrooper armor, show them a droid that looks sufficiently similar to R2 (even if it also looks like a soccer ball at the same time) and they are instantly on board.
That's the power of nostalgia at work and I admit seeing that concept art of Ripley and Hicks worked for me in much the same manner. It's little wonder then, I suppose, that Hollywood is so keen on sequels and re-makes. They're guaranteed to draw in crowds. Even when those same crowds have been let down by earlier sequels and re-makes, they're always willing to give new ones a chance.
And I agree with you, Cat's Cradle. It is a little hard to believe that it's been thirty-six years now since the original came out. However, the really amazing thing about it is that it still looks good after all this time and I can easily imagine it thrilling new viewers in another thirty-six years.