I wouldn't call all of those "arcs." A mystery about who killed Asmodean has mostly become a joke...something that RJ realized his fans were obsessed over and wanted to treat them to the excruciating wait. Similarly, Moiraine's death isn't an "arc"...it's something that happened, and she'll reappear at a key moment during the Last Battle, I'm sure. Despite her mistakes, Moiraine has dedicated her entire life to fighting the DO, finding Rand, and preparing for the Last Battle, and we can be sure we haven't seen the last of Moiraine.

Demandred, similarly, has been saved for the end. The Forsaken have been picked off one by one, for the most part, with a book or so dedicated to each--TFoH for Asmodean and Lanfear, Crown of Swords for Sammael, etc. Demandred's story hasn't been developing, but our curiosity certainly has.

As for the Perrin and Elayne storyline: I completely agree.

Another I'd like to throw in is the damn Morgase "hiding away" as a maid story arc. Seriously, hurry it up. Siuan and Leanne's similar story went much quicker!