My take is that Congress is about publicity, not prosecutions. So whatever they do (in either the Senate or House) is really more for show. That's not to say they're not important (the transparency and disclosure that comes from hearings is important), but they're not going to lead to anything in terms of prosecutions. BUT, the fact that they announced the subpoenas today is a likely sign that Durham is done and has given them the greenlight to do so.