We have asked the same question here many times and in the process distinguished the working class and the universal class: the latter is simply the class of all classes (a set theory analogy) and includes the working class.
An emphasis on this view of class might give the left a broader perspective on the more complex structure of society with a question about how social diversity will enter into a socialist outcome. We can’t just say that the working class should take over society and turn the rest of society into an inferior set of classes. We might consider that all classes merge in a socialist context into the ‘universal class’ redefined in a socialist context.
Challenging the working class idea is a form of dialectical debate, not a divisive rejection of the brilliant history of working class radicalism. But we should note the failures of the ‘working class’ concept. The working class is often as conservative as the bourgeoisie. The classic strategy behind working class radicalism maintains its key significance but we must not reinvent class inside socialism as with the useless idea of the ‘dictatorship of the proletariat’, an idea created and monopolized by a marxist vanguardist elite.