This discussion involves details about content referenced from another domain (or source which is not trusted). The implementation seems to be an issue which has finally been solved with a standard. The new implementations are being worked on. It is called CORS and the problems are still hard to solve in practice.
I am super glad for all the hard work put into all this.
Oh gosh, that is absolutely true. A major change in presentation when the support is dropped to be sure. On the other hand, what was the level of standardization then? Were there not massive inconsistencies across browsers when you got into fine details of implementation doing frames? Especially parent-child -relations among elements/sets/contexts which is an integral concept in definitive DOM - a grand achievement in standardized HTML format.
So every move cannot be precalculated? Some of the constraints may be there. The completeness of information available would be the definition of breakthrough for me. In this case, the first state of the game is presented in total with 100% accuracy. So are all the steps from there onward. In my opinion, the challenge for a breakthrough comes when most of the actions of other players happen in dark and no feedback is presented to the AI.
In a lifelike situation the AI will not have access to the inner state of the game, but instead has to gather the information via the same (restricted) mechanisms as other players.
edit: I should probably clarify that the above is about competitive StarCraft. I should probably learn to play GO, too.
The "plenty of great websites" were developed long time ago. Having a degree of visual consistency of layout across different browsers was not possible then according to standards.
The content will not be lost. The tags will result in valid elements but the rendering may vary. This has always been a thing to be expected, since legacy elements (pre HTML5) never had uniform rendering and contained quirks.
Should the current/new standard have support for ambiguously rendered quirky elements? Is it even a standard then?
After HTML5 the end result will definitely be the same on most (if not all) layout engines. The standardization as a process requires non-conforming legacy to be dropped.
An AI which excels in imperfect information games (card games, Starcraft) would be a real breakthrough. Raw calculation power is bound to win games with a finite set of possibilities. The huge leap would be the ability to handle probabilites: taking guesses, making assumptions and coming into some kind of successful conclusions based on those.