How would you go a year without camera or lens purchases, regardless of intensity of GAS?
Selling is acceptable.
But no purchases.
Buying and processing film is okay, so is buying and using consumables for printing digitally.
There was a financial advice columnist that answered subscriber's questions in the local newspaper. One answer has stood out for me. A subscriber stated that he had some "extra money," and wondered what to do with it. The columnist replied, "There is no such thing as 'extra money.'"
To get away from the grip of GAS, and the buying of more gear than you can use, realize that the money really should be going somewhere else more important. What area of your life should have a higher priority? Once that higher priority becomes real, there won't be any money for new cameras and lenses. It is not fun. But it works.
Another method, for just one year since that is your goal, is to write up a schedule for the use of your existing gear. Say you have 12 cameras (and it appears that you do) and you use each one for only a month, you see two things: 1) Using a camera for only a month is not really very long, and 2) It is a long time until you get to use that camera again. Then, when tempted to purchase another camera or lens, you will ask yourself, "But when will I ever have a chance to use it?"
I've used both these techniques this year, after about 5 years of acquiring more gear than I can possibly use. I've still filled out the missing pieces, so haven't been totally free from spending more on gear, but I have slowed way down.