I'm not yet sure if I wholeheartedly agree with GP but, it would set some limits. For live performances, yes, you'd get a usual fee as per number of hours preparation and performing. No matter if you play a cover or original work. The fee could still be negotiable, so performances with a higher demand in the market could ask a higher up-front fee than those not. Every person involved in such a show of course have their own wage. Many are fixed by their contract, job description and thus their expected performance. And when they go 'above and beyond' (like overtime and/or producing more results), they should expect extra pay. But those of creative performances where each performance can differ to the next, could float depending on the quality delivered, if the performers want to enter an agreement in which they are evaluated as such.
Then, for creation of new works (whether it's by inspiration or aspiration), you could imagine a one-time fee to the creator is in order, which can be very large due to perceived popular demand, especially for established creators with a large fanbase, but it will be one time fee. When it's set, we know how much it costs to 'buy out' a certain creative work and when enough 'copies' have sold to cover the costs, the material enters public domain. Remaining value stays on a balance sheet somewhere and has to be property taxed so the fee can't be set too high, else the entity holding the work will go bankrupt. When a work then isn't or can't be transferred to another entity for x clamshells which can not be more than the remaining value, it also slips into public domain. No zombie works allowed.
The value of a creative work can be limited by the amount of time and resources spent to get to make the creative work. Time spent, of course, has a limit of your 'usual' lifetime for your first created work, substracted with hours unavailable to spend on creative works or some other metric, set by law and if you can validate the claim your first work also is your 'life's work'. If you create multiple works, you can not count your hours double but you can split them. No problem working at multiple projects, just not exactly at the same time (to create asks your undivided attention). Resources spent can be limited to services and raw materials spent creating the work and handed over when the fee is negotiated (so no stating the work consumed 3 gold bars to create when the gold isn't an actual part of the work, handed over). Unless you can successfully claim there is waste, in which case the value of that waste has to be evaluated and deducted...
Well, that's five minutes spent on how such a system could work. When we have centuries, as with the current system, we could figure out something reasonable, I think.