How long until Node can actually and effectively replace a Java backend, though? And all of its business logic?
Talking about a complete JavaScript full stack, even in the business area.
I think it depends on the size and complexity of the original application, as well as the skill, experience and knowledge of the team(s) doing the work.
In this case, it looks like around 2.5 years for cars.com... My experience tells me at least 6 months for a moderately complex application. I've replaced a few microservices in days.
I didn't mean an estimation for replacing a Java backend, but rather how much time will pass until Node will be considered a common and valid alternative to Java for building the business logic of an application.