I don't want to be too controversial but if the current (albeit
anecdotal) course of events is that XML is waning in Web
use
As a Web interchange protocol it never was very strong. As an essential component of back-end processes that lead to the Web, it is still very important. The chance that W3C will deprecate or drop its XML standards is essentially nil, and if it did so by some freak, many nimble organizations would instantly leap to the rescue without waiting for ISO to act.
On the reception side, a few organizations can only make use of a standard if it's a recognized International Standard, or at least a standard from an international standards body, but most people don't care if the standard they use was issued by ISO or the East Grong Grong Sheep Ranchers' Association.