Palma town hall initiatives to help small retailers have "not materialised".
An increasing number of establishments are up for traspaso.
The European Commission is meanwhile advising people to wait before making holiday plans.
The 15% estimate is for when the state of alarm is lifted; more closures will follow.
Some hotel groups are said to be already writing this year off.
"We'll have to get the hotels open first, hopeful that there can be flights and a good September."
Bars and restaurants
Restaurants want more help than just an elimination of the terrace tax.