If there was anything tangible at this point, we'd all know about it.
The prime target surrounding the collusion narrative has been Michael Flynn, but at this point we know that his conversations with the ambassador (that people on both sides had, since...you know, it's his job) didn't amount to any actual collusion and he was cleared. Even the Washington Post admits this and they're not exactly unbiased:
https://www.washingtonpost.com/world/national-security/fbi-reviewed-flynns-calls-with-russian-ambassador-but-found-nothing-illicit/2017/01/23/aa83879a-e1ae-11e6-a547-5fb9411d332c_story.html?utm_term=.82e90b77f7eb
Basically, the entire investigation is based around people talking to someone who's Russian, at some point, about anything. That's all we've heard since the initial Flynn angle. Yet there's no smoking gun after 8 months and they won't find one 12 months from now either.
The Watergate investigation may have taken 2 years, but that was over 30 years ago. Information moves a hell of a lot faster now.
Again - I'm not American, I'm not "on the right", I don't have a dog in any fight here. From an outsider's perspective, the entire thing has become fucking hilarious to an extent, with CNN's constant "BREAKING NEWS" about Russia, but the longer it drags on the more damage it causes - and I don't mean to Trump. The Democratic party is dying and instead of trying to pull itself together it's dragging along with this entire narrative. I really don't understand the point in continuing in this direction, he's not getting impeached. That's a pipedream.