I don't think it's corporate-speak. To my understanding the use of "sunset" as a verb comes from law where contracts and laws sometimes have "sunset clauses" e

I don't think it's corporate-speak. To my understanding the use of "sunset" as a verb comes from law where contracts and laws sometimes have "sunset clauses" ensuring they become defunct at a certain defined point in the future. From there, "to sunset" something seems a fairly logical next step.