I think society will decide what value each Input of labour has according to the needs of himan beings to live happy healthy sustainable lives. There will obviously be tasks that would be less desirable to do that require doing such as unclogging the waste treatment system, and there will be other tasks that will require massive commitment to education before they can be performed such as brain surgery. In a dirreferent thread I spoke about the movie i watched on youtube called The Secret of Oz. In this movie they talked about what existed before money. One of the things they spoke about was used in England of old. They simply used sticks!. The sticks were of different sizes and were split down the middle. Each time you performed a task of value your half of the stick would get a notch, along with the other half. As the stick filled up with notches you would move on to a thicker stick and get a notch, much like an abacuss works (an primitive counting device). These notches were then traded for godds and servides you aren't able to provide for yourself. Ofcourse there had to be a repository for the second half of the stick to make sure no one fraudulently notched their stick, and this was held locally. I am not suggesting this is a future ideal to replace money, i only state it to describe what existed before money to provide a way for people to earn value fro what they contributed. Something would need to be introduced because unfortunately not all humans are capable of alturism, or desire to be alturistic all of the time. I used to belong to a baby sitting club. I earned a token each time I baby sat and could use those tokens to get my own children baby sat when needed. This wouldn't work in a moneyless system because of the different values placed on different types of work due to unpleasantness, or time commitments associated with education as I stated before.
It's an intriguing problem to come up with something, but coming up with something is what's required because people can't provide everything they need by communally living on acerage somewhere in a modern world. The desire isn't to go back completely to an agrarian society, but to live sustainably by making the best use of resources and technology.