I'm sorry that the note caused you concern. Only the Optimization app ( optimtool) will be removed, because the underlying software that it relies on is maintained minimally and will cease to work at some point. The solvers such as ga and gamultiobj will not be removed. Indeed, we are actively developing our solvers, and expect to continue to do so.
As to whether the app will be replaced, well, I cannot comment on specific future plans. Sorry.
MATLAB mathematical toolbox documentation