We already lost the W3C once for about 10 years. Remember XHTML and XHTML2? Those, and a bunch of special purpose not particularly interesting niche XML standards (P3P? XML-FO?) were pretty much all they worked on for a decade or so. It wasn't until the WHATWG was formed by some browser vendors who wanted to start working on a standard for features that users would actually want, rather than what architecture astronauts thought would be a nice design, and the W3C realized that's what people were actually interested in and so replaced XHTML2 with HTML5 based on the WHATWG spec that they actually became relevant again.

Now, I will have to give credit that there were still a few groups at the W3C doing work relevant to the actual open web, such as SVG and CSS. But given how the WHATWG took over work on the HTML standard and actually did work towards a standard that was useful and relevant to browser vendors when the W3C went off the rails the last time means that I'm not too worried if it goes off the rails again this time, you can always form another standards body if it becomes irrelevant. You just need to be sure to recognize this early on, so you don't waste too much time and effort waiting for the W3C to get its act together again.