Arcanist’s purpose is to sell the game, “casual” or “new players” being the primary target. Based on this, Arcanist will be easy to be competitive on. Arcanist will out-damage, out-heal, and out-sustain DK, and with less effort.
I like the idea behind OPs post: make a class that rewards highly-skilled play. Not sure I agree LA is the only/best option for doing that, but I agree in principle.
Arcanist would be the perfect time to focus on new ideas for combat, to not require LA weaving at all. In all other classes LA weaving is already the best performing way of playing, so why not bring in some fresh ideas from Apocrypha?