Once HD DVD and/or Blu-ray players reach a substantial installed base, I'm sure we'll see quite a few operas on HD. But only performances since 2000 +/- will have been recorded in HD. Even before this year's Met HD at the Movies, some Met performances, such as "Salome", have been recorded in HD. I think it's VERY likely that the Met performances WILL be released in HD. Someday.
But as mentioned above, Opus Arte expects to release operas in HD later this year. Initial plans are for 3 operas on HD DVD. (Perhaps since the cost of mastering and making HD DVDs is less than for Blu-ray.)http://www.opusarte.com/pages/opusarte.asp
Opus Arte: High Definition - leading the way
Opus Arte has been recording in High Definition for over six years and has amassed a substantial catalogue of outstanding productions from around the world. The High Definition debate continues to evolve. We have already seen the launch of HD players in America, Japan and Europe, and with the arrival of Sky HD into the UK market we can expect things to develop very quickly.
Opus Arte led the way by being the first company to release a Classical HD DVD into the world market, and plans to issue Blu-Ray DVDs are also in the pipeline.