I just read the official Q&A for last month and I have to say - I am a little worried about skill decay. I hope it will be done by certain amount of xp in that skill, not by a percentage. Because with amount of work it takes to get a skill to 100, it would be for me on a verge of rage-quit if i loose all that work to the skill decay.
Over all I think that skill decay in a game where it take considerable amount of work to raise a skill is a bad idea. Skill decay is imho for a games where it takes you like 1hr a day max to keep all your skill on the level.