Yeah, but if the big value is supposed to be in the libraries you sort of have to accept dependency hell? Otherwise you're in the world where a small set of libraries can deliver all the functionality ever needed.
Of the currently available solutions, "cloud environment made by Microsoft" doesn't sound that different from "software update made by Microsoft" in terms of how it solves the dependency hell: basically, the critical library you need is either in or out, but there is nothing you can do about it.
Admittedly, here I'm assuming Microsoft won't let you install things into the environment yourself since that basically means hosting virtual machines running arbitrary code and putting the Excel brand in front.
