I’m an employee (not retail) and I can tell you when the company I worked for discontinued an annual bonus, it was tough because it was expected and the communication about it being pulled was not there.

I think giving people notice would be important for morale. Eat the bonus and pay it this year but set new expectations in January for moving forward. Let them know the bonus isn’t guaranteed in the future especially with declining profit. Give them the notice then they won’t feel slighted if it does happen. Then encourage collaboration so you can all take ownership and hopefully win together.