I think in the end, deciding to not support something is really a power they have, since this decision will influence the developers in not using that something. If IE won't support websockets, we won't use websockets because of lacking support in IE, so it's not really that big of a deal to them (the average end user doesn't decide what browser to use based on what support it has for web sockets)
Indeed. I also don't think any clients will accept dropping support for IE6-8, so the IE9 release, whilst nice, will never be a limiting factor in feature support.