Standards are made by first-movers even if what they move is howling junk. Every technology has been immature when first brought to market. What we need to be looking at are the obstacles to maturation, which seem to be increasing.

That kind of answers your title question. Without a contender, there's nothing to replace them with. I do agree with the rest of your comment, though, it'd need to be something that could be implemented and used in parallel with the existing standards. Ideally something near isomorphic to them so that browsers can mostly just do a translation to get a good enough initial implementation, and then refine it over some iterations if the underlying HTML/CSS/JS models don't cover all the things in the new system.

Also, are you meaning a contender would replace all three with one new language, or would it be three new languages that are (somehow) better than the three existing languages?