Probably the neo-Luddite movement will begin. Nobody wants to starve to death (and these are the criteria we have now adopted for the general working mass of people for bread and water).
Will find another job. Of course, for some time after robotization, unemployment will increase, but this is temporary.
Think about this: No one has created or adjusted this world for us (for workers). It is we who always adjust to the situation, and it has always been this way and will probably continue. And in this case, people will also adjust and find something.
Also, we must not forget how theories and predictions are destroyed about reality. Of course, now it seems to someone that robots will do everything, and people will have nothing to do. In reality, most likely everything will not be so. And robotization will be introduced gradually and not all at once in all areas. That is, it will not happen that robots will suddenly appear everywhere at one fine moment and people will start clutching their heads in horror. And if this is gradually introduced, then people will have the opportunity to adapt to the campaign of the case. Someone, of course, may find themselves in a deplorable situation (yes, even now many have problems with work and without any robotization), this is a fact, but so that everything was totally and hopeless like this ... hardly.
Yes and frankly speaking, no one really holds on to such a work of the type you described. No one has been working there for decades and everyone (well, almost everyone, okay) one way or another strives to find something better or to get a qualification that will allow them to go to another field.
In addition, by the time robotization will reach its peak already new works will appear. And in general, the extinction of jobs and professions due to progress is something natural and inevitable. And people in history have faced this more than once.