Here's the thing, even if the dossier was fake, it prompted the FBI and intelligence agencies to take a hard look at some things, that look seems to have turned up at least enough information to warrant the investigations continuing.  As I have said before, I don't know if anything is really there, but it certainly seems that there is.  

Trump ultimately could end this tomorrow.  He could publicly offer to hand over every bit of information that any investigator could want.  Make the offer loud and in public, let the Special Counsel and the House and Senate have everything they could want, and leave it at that.  Instead, he keeps acting like someone who is trying to hide a bad act.  The longer he hangs on and acts guilty, the more likely they are to keep digging and find something, even something unrelated.  Remember that Nixon went down over the cover up, not the break in, as did Clinton, it was perjury and obstruction, not the affair or whitewater.