Originally Posted by
Yuyn
They'll probably use the modern UI and API, with most features that weren't available in Classic disabled and hidden (calendar, dungeon finder, etc.). I'd still expect to see some of the more modern changes stay though, primarily stuff that was already possible at the time via addons (such as the improved raid frames) and stuff that improves accessibility for impaired people (readable fonts, colorblind mode, high-res support, etc.).
And the API would almost certainly be just as restrictive as it is now or people will just do all the same trivializing stuff that makes the modern game 'too easy' in their view, except in a game that was objectively much easier in terms of gameplay and mechanics (with the vaunted difficulty of end game mostly coming from organizational challenges of 40-man, people just not knowing what to do, and much more restrictive gear checks/gear gating).