Isn’t it more appropriate to turn their investigation’s work product over to a post-Jan 20 Justice Department and get back to legislating?
No, and here's why - if it's Justice, it literally has to be brought to a somewhat speedy conclusion, because even one indictment returned to bring pressure on principals triggers 6A.
OTOH, the House committee can simply meet, gather evidence, meet again, take testimony, meet again, make news releases, meet again, all the way up to 2018. This kind of red meat (albeit hamburger) polls well.