To some extent, I think they now see it as being in their own interests to pay more than lip service to standards. Only to some extent, of course. Netscape is trying to convince the media that they aren't dead yet, so they are a little distracted at the moment. But I think that HTML 4.0, including CSS, will fare well in the next version of the big two browsers. I'm pretty sure we'll see some areas of difference, but overall I think the browsers will converge as far as how they render web pages.
Developers are, on the whole, self-centered creatures.
They will use whatever tools they perceive as best for them, not the industry, to be blunt. They have learned it is in their own interest to pressure the big vendors into honoring standards more than the vendors have done. I think that is where the real pressure is coming from. I do not think it will replace HTML, as some people have claimed, since they are different things. One of the most powerful aspects of HTML is how easy it is to learn and use.