I know a couple of engineering teams at Apple that are working on new projects in Scala, while also maintaining some legacy systems. Some of these projects are quite critical to the company’s ecosystem, e.g. test systems. I’ve spoken with several engineers who helped create these systems years ago; they’re all now in senior management positions. Some still stand by the technology choices made back then, while others are more open when given a chance to reflect. The general consensus is that if Kotlin had been available at the time, or if Swift had been a viable option for back-end services, they definitely wouldn’t have chosen Scala for those projects.