Are you planning to get back to doing the things you did so far or are you considering leaving the forum?
Both options are not excluded.
What happens if a merit source stops meriting posts? Are they booted out?
Nothing will happen. Merits available for distribution expire after 30 days and new ones appear in their place, in the same quantity in which they were previously available.
only that members may not merit you too as you are not involved in the system, but as a merit source decision to stop meriting posts sounds like 'quiting your job'.
This is the most stupid thing that Merit Source or any other participant can do, not give out Merit simply because someone else does not give it out either. The merit system is not barter on the basis of you to me, I to you. Merit is needed to evaluate posts, when sending it, you need to take into account ONLY the value of the post, and not the user's nickname, what he does on the forum, whom he added to the trust, how much he distributed to others, and so on. These are things that do not belong to the merit system.