Probably the introduction of DRM so Hollywood would start using video tags instead of flash/silverlight/other plugins. It’s a pragmatic approach, but right now it’s incredibly limited for anyone who wants to make their own browser that can load Netflix.com, for example. The only folks DRM punishes are those trying to do the right thing, everybody else can find workarounds if they need to.
The Electronic Frontier Foundation resigned from the W3C for a reason.