Suppose Comey's investigation turns up irrefutable evidence that the Russians did in fact seek to subvert the election. This could be actual tampering with vote counts in some way, or general attempts to push opinion in one direction.
Those are two
very different questions...(And as bad as the second point is, the first would be
far more serious and worrisome...)
On the first point, there has never been any serious evidence put forward, or a report made by any official in a position to know, that the Russians actually successfully hacked voting machines and were able to change votes.
Your second point, "general attempts to push opinion in one direction" is a confirmed fact. It's been confirmed publicly by a number of intelligence officials and agencies, most recently again by Comey on Monday.
But the problem of course is that unlike
direct hacking that results in phony vote counts, (for which there is no evidence) it's impossible to quantify the effect of the release of the emails Russia hacked on the outcome of the election.
Obviously, it didn't help the Clinton campaign, (my personal suspicion is that given the content of the emails that were hacked and released, it didn't change votes so much as maybe suppress some of the vote from Sanders supporters ) but was the negative effect enough to be responsible for the election outcome? This is an unknowable. (Afterall, there were
many other factors influencing that election, pro and con on both sides.)
These could be with or without the connivance of the Trump campaign...
... I suppose if it could be proved that Trump himself in some way directed the effort we could go the impeachment
Determining whether or not there was/is collusion or a quid pro quo between Trump and the Russians, (not just on the effort to influence the election, but also on the pro-Russian policy positions Trump has taken) is the primary purpose of the investigations currently taking place. (Diversions that Trump and others try to throw up notwithstanding)
That's the $64,000 question, and if clear proof of this is uncovered, I expect he
will be impeached and removed, or resign to avoid that fate. (Like Nixon did)
(I don't suppose that it will come as a surprise to anyone that I am fervently
hoping that this turns out to be the case. This is
the one issue that, if there's real substance to it, could bring an early end to his Presidency.)
is there anything we can do besides wring our hands?
Even if it turns out that strong evidence Trump colluding or coordinating with Russia isn't developed, there are
absolutely things we can and should do to punish and retaliate against the Putin regime for its outrageous attempt to influence a US Presidential election.
Publicly we should be increasing sanctions, (the ones imposed by Obama on his way out were his usual "day late and a dollar short " sort of "action") and we should be working with our allies (who have also been subjected to Russian election meddling) to do the same.
Privately, we should be planning and executing a cyber attack op of sufficient magnitude that it will serve as a deterrent to any further such attacks by Putin. ( One creative idea that occurs to me would be to track down some of his bank accounts and those of his oligarch pals, and transfer the money out in a way that they couldn't get it back...
That might get their attention...then we could take the funds and give them to the Ukrainians...

)
The problem with any measures like these being taken of course, is that they would require the cooperation of Donald Trump...
And that ain't going to be forthcoming...
So the answer is yes, there are many things we could and should do, but they aren't to happen as long as Donald Trump is President...