dead: browsers from last 2 version query, but with less than 0.5% in global usage statistics and without official support or updates for 24 months. Right now it is IE 10, IE_Mob 10, BlackBerry 10, and BlackBerry 7.

Even with not dead, browsers like:

• QQ Browser 1.2 (0% market share)
• Android Browser 62 (0% market share)
• Baidu Browser 7.12 (0% market share)
• Opera Mobile 12.1 (0% market share)
• Opera Mobile 37 (0.01% market share)
• Opera 49 (0.02% market share)
• etc

I think that the AND condition is the problem.

• It's good because it means a version of chrome released 1 hour ago with less than 0.5% usage isn't considered "dead"
• It's bad because a browser that was released less than 2 years ago but has 0 users isn't considered "dead"

Alternatives:

• "deadness" score
• "dead" is determined by age exceeding market share