Standalone emulators are continuing to make progress for each of these platforms, but there's still quite some way to go. Once we get those to a level where most games are playable without issues at full speed porting them to the browser would theoretically be possible (no idea about the speed hits though), though I don't expect that to happen for several more years.
As for the Internet Archive itself, they recently set up their Internet Arcade: Turbo Edition [1], a collection of arcade games from the 90s and early 00s that cover the most demanding emulated games playable in the browser on the site (apart from Dottori-kun, of course).