I have some ideas already:
The FARMER could pick being able to restore farming plots more quickly, being able to make preserves, gain more crop yield, so forth (I wasn’t able to think that much for this)
The TRAPPER could take the Baited Traps feature, which allows him to use vegetables (Level I) and grain/corn (Level II), if available, to trap animals with more efficacy; alternatively, they could choose between getting more meat from an animal (Use Every Part) versus being able to get more leather and other non-food resources (finer cuts).
The CARPENTER could have passive traits called “downtime activities” which confer benefits to the entire town; for instance, he could choose to create a set of simple tools in his downtime which improve plant gathering speed by workers, or he could improve his crafting speed in specific tasks which involve plank-like structures (beds, chairs, furniture gets a crafting speed bonus)
The STONEMASON could have a similar downtime activities where he makes, says, chisels which allow workers to harvest more stone while retrieving the same amount of ore, or have an Grindstone ability which gives a bonus to the damage of footmen and knights.
However, I’m concerned that I do not have enough ideas for perks which have to do with the professions themselves, like in the current systems. Suggestions are not only welcome, they are what this thread is for. Have at it!