They go up every year. So does everything else, so the fees must also.
Some resorts manage to keep the MFs low enough but I have had some resorts that have likely gone up 75% in a total of 5 years. Others have horror stories about climbing MFs as well, and will likely chime in.
Special Assessments happen if units are not cared for well and reserves are underfunded. Some TS do not do a good job of having reserves and just have special assessment when they have something big that needs repair.
Special Assessment can happen with also Natural disasters, hurricanes, floods etc, where they may be insurance but the deductable in under funded or not funded in the reserves.
Sometimes when management companies are switched at a resort, new management companies may charge a special assessment to get the resort back up to a minimally accepted norm for that system, eg, Wyndham, *wood, Marriott may be more apt to have that kind of special assessment.
So expect fees to go up.

If the remain the same bonus,

if they go down, throw a party.
