Competent software engineers can work with more than one RDBMS and they can port your application to a different system.
So if leadership really wants to make a change, they certainly could.
Postgresql, DB/2, TeraData, MSSQL, SAPDB,...
Of course it helps to stay clear of proprietary extensions like PLSQL. And to test the application during development against several different RDBMSs. Then you can switch at low cost.