I expect to hard-deprecate everything marked `@deprecated` before 1.39 is released, and then actually remove the hard-deprecated methods in 1.40 (just after the 1.39 LTS).
To hard deprecate:
[x] `::getOutputHooks()`
[x] `::addOutputHook()`
[] `::addJsConfigVars()`
[x] `::setFlag()` (hard deprecated in 1.41)
[x] `::getFlag()` (hard deprecated in 1.41)
[] `::getCategories()`
To remove:
[x] `::getCategoryLinks()`
[x] `::setCategoryLinks()`
[x] `::getOutputHooks()`
[x] `::addOutputHook()`
[x] `::addWarning()`
[] `::addJsConfigVars()`
[x] `::addTrackingCategory()`
[x] `::hideNewSection()`
[] `::setFlag()` (no sooner than 1.42)
[] `::getFlag()` (no sooner than 1.42)
[x] `::setProperty()`
[x] `::getProperty()`
[x] `::unsetProperty()`
[x] `::getProperties()`
[x] `::hasDynamicContent()`
[x] `::preventClickjacking()`
[] `::getTOCHTML()` (hard-deprecated in 1.40)
[] `::setTOCHTML()` (hard-deprecated in 1.40)