I think it would be nice endgame content if we could eventually pick a trade and unlock the ability to produce masterworks in that trade. Stuff like being able to smith as a trade is a common example, but being clothier, or wood worker (produce masterwork carved, or wood integral items like arrows, bow's, and the like), instead of just being stuck either being able to produce masterworks or not. It might cap what a single character can do which many would see as undesirable, but it could add diversity to characters.
Basic idea would be that a jack of all trades, master or none would only be able to produce decent works of all things, but the ability to craft or procure masterworks of a set of items would be attainable.
Right now, I know characters with maxed skills are currently able to produce masterworks of furs, leather, and foods of all kinds.
There are other products that I suspect you could create masterworks of but I'm not fully sure. I'm not sure if board creation quality for instance is capped at decent, and I'm not sure if it's timber-craft or carpentry skill that governs it's creation quality, weather it is capped by the quality of the trunk or log (or if it isn't via an internal no quality tag). If you can get boards and staffs at masterworks quality you can add those to the above list, as well as paw-boards, and paddles.