While XForms has unusually large number of implementations at draft stage, I have little hope for XForms replacing DHTML. Benefits of XForms are not compelling for most web applications and there are complications that prevent wide deployment as a web technology.
Server-side implementations hide XForms behind other readily deployable technologies by generating instance-specific DHTML from XForms. Unfortunately, this approach alienates web designers and hands-on-the-metal developers who likes to have full control over DHTML.
Client-side implementation can be either installable or zero-footprint. Install approach has the obvious distribution problem. Zero-footprint approach, typically implemented as Java applets, Flash movie, or general DHTML-based engine often result in usuability problems such as forms loading slowly or sluggish UI.
I still think XForms can be of value in niche markets, but I see little chance of it taking off in horizontal markets unless Microsoft builds a XForms engine into IE, basically same story as SVG. I mean what compelling incentives are there for Amazon, eBay, or Yahoo to deploy XForms?