Re: "but we will always have at least the original black box's capabilities."
Yes, I'm sure. I'm sure because already "serverless" doesn't mean "Amazon". Serverless has a lot of ardent followers, and they're building open source solutions that do what Amazon's Lambda does.
Similarly, machine learning, AI, BI and other BDCA tools are seeing a lot of open source growth. In short: a commercial entity (like Amazon) might come up with the initial concept and get to milk it for a while, but all technology eventually ends up democratized.
The basic approach of serverless - white simple scripts (or have a UI/digital assistant write them for you), and have those scripts simply pass data from one black box to another - isn't going away. Humans don't typically uninvent things, especially in IT.
The increasing adoption of digital assistants also makes this seem like a permanent thing to me. The black boxes used by serverless types are really no different than the "skills" one can build for Alexa. Indeed, many of those skills are nothing but serverless scripts that call black boxes, and I've already seen Alexa used to create new serverless apps, which could be published as Alexa skills...
The whole thing has already reached critical mass and started a cascade. While a bunch of whingy nerds who can't disconnect "application development" from "enterprise apps" might not get the importance of an ever-increasing library of digital capabilities that can be used by any Tom, Dick or Harry, non-nerds seem to get the importance really quickly.
So we, IT nerds used to the way things were, we might not see the utility, or ever get around to using serverless to do our jobs. Our kids, however, will use serverless-style tech to do all sorts of stuff. Using - and trusting those black boxes will be as natural to them as smartphones are to my generation, or staring blankly at VCRs flashing 12:00 was to my parents' generation.
So sure, in the short term I expect some of these black boxes to disappear. That will lead to a backlash, and to standardization, to the development of "skill libraries" and all of the predictable evolution of responses to this problem. Corporate greed is eventually overcome in tech, even it takes a decade or so for us to get our shit together.
It is very early days for this technology yet, but the basic approach is sound. And those who have used serverless in anger tend to become adherents pretty quickly. Even the disenfranchised and cynical nerds.