I doubt that they Touch this Demo built much.
They are working on their true Branch I am Sure. Some modules such as classes might get added into this Demo branch further down the Line though..
I Just Hope they do Not add too much, cause i want the real Thing on Release rather unspoiled with new eyes.
Arguably, all mechanics that are intended for the full release should at least be partially implemented in the EA before everything is finished, so we as players can actually test them and provide feedback on their implementations. Same for at least the start of most major companion storylines, like with Astarion and Shadowheart so feedback can be given there.
However they did say awhile back that EA we are intended to only have Act 1, so even if all I hope is added, you eyes will not be spoiled of the overall story.