i suppose its good that they are doing it for precedent but it wont amount to anything, its already known that trump told him to fire mueller and then told him to lie about it, and nobody gave a fuck then, and the democrats were too feckless to do anything with it.
i dont imagine its going to change any minds, and even less people will give a fuck now, so its all just political posturing. what do they think they are going to get that mueller couldnt? even the topics that they can ask about are severely limited.
i would put the chance that any bombshell news (or even interesting news) comes out of this at about 1%.