Indeed, this is how game developers work: hired in legion strength to push a game to release, then laid off once it's released.
I've heard that DLC has made this less of a problem in recent years. Since there's a stable, predictable revenue stream and delivery channel for new content, iit's much easier to justify keeping devs, designers and artists on full time. Presumably this varies by studio / publisher / genre, but my impression is it's much better than it was.
Yeah, there is certainly a parallel argument to be made about constantly introducing new tech even if the currently used tech is GoodEnough.