That's why I wrote "not saying she should fund the whole thing."
But a commitment to part fund wouldn't hurt the project. I'm pretty sure that a Sigourney Weaver produced Alien movie would be warmly received in many quarters and I'd be very confident she'd get a good ROI.
Would it have to be a hugely expensive movie? Prometheus was, of course, would they need to spend 100 million on Alien5? Maybe they would (I know that - maligned as it is - AvP was done pretty cheaply and looked pretty good).
But, that's all pure fantasy - I doubt if she would exec produce, I guess its just wishful thinking on my part.