If a tool were created that properly converted an UML diagram into a project without any need for code, all the programmers that lost their job to this tool would then be hired by the company that offered it, in order to give maintenance and support to everything the customers want in their programs.
It would be removing programmers from they payroll of some companies but they would still be working for them, just further down in the chain.
The same is true for AI. If AI could completely replace programmers in some area, it would need a lot of programmers itself to keep dealing with all the edge cases that would show up from being used everywhere that a programmer was needed before.