I think it's fair to say that some liberals are a little too excited at the prospect of Trump getting impeached -- it's not clear how that could happen feasibly as long as both Houses of Congress are controlled by his party, for example, let alone the fact that as yet he's not been personally implicated in any of this.
Still, it theoretically could happen. Mueller's investigation is probably not going to lead all the way to the top but if it catches in the net many of Trump's supporters and colleagues then he will still personally be affected by association. It will also be interesting to see how Trump reacts. All along the investigation there's been talk of Trump, directly or indirectly, firing Mueller and (effectively) killing the investigation. Even now some, such as Newt Gingrich, are calling for that step. Such would be a gross conflict of interest -- firing the guy who's potentially investigating you?! And yet Trump already did that once this year, when he sacked FBI Director James Comey.