Maybe Comey is continuing the investigation to blur his own role in the Obama administration's improper and illegal snooping on his party’s opponents. He has not closed the investigation despite its apparently flimsy basis, perhaps to protect himself. He was supposed to report this investigation in a timely manner to the Congressional and Senate intelligence committees and did not.
As a correspondent with some knowledge of these matters related to me:
“When push comes to shove, no investigation gets opened, no FISA order is applied for, without James Comey's say-so.  They can bluster, but it's damned hard to get rid of an FBI Director without a very, very public stink.  He could have said no, but he didn't.  That means the investigation is bound to focus on him.  And count on it -- the decision to short circuit Congressional oversight was probably pushed on him by those same people, but once again, it was ultimately his decision.  He could've gone to the Committee, but he didn't.  His decision, his responsibility.”
His view is strengthened by Comey’s obfuscation at a Congressional hearing:
The counter-intel investigation, by his own admission, began in July 2016. Congress was not notified until March 2017. That’s an eight month period – Obviously obfuscating the quarterly claim moments earlier.
The uncomfortable aspect to this line of inquiry is Comey’s transparent knowledge of the politicized Office of the DNI James Clapper by President Obama.
The first and second questions from Stefanik were clear. Comey’s understanding of the questions was clear. However, Comey directly evaded truthful response to the second question. When you watch the video, you can see Comey quickly connecting the dots on where this inquiry was going.
There is only one reasonable explanation for FBI Director James Comey to be launching a counter-intel investigation in July 2016, notifying the White House and Clapper, and keeping it under wraps from congress. Comey was a participant in the intelligence gathering for political purposes -- wittingly, or unwittingly.
As a direct consequence of this mid-thought-stream Comey obfuscation, it is now clear -- at least to me -- that Director Comey was using his office as a facilitating conduit for the political purposes of the Obama White House. 
John Brennan
It’s possible that the tissue-thin, incredible Steele “dossier” was not the only disinformation source. At the Spectator there’s a plausible account of how Obama’s CIA director John Brennan worked with Hillary and certain Baltic figures to discredit Trump with the charge of collusion with Russia. 
Brennan pushed for a multi-agency investigation of the Trump campaign, using as his pretext alleged intelligence from an unnamed Baltic state. That “intelligence” was supplied at the very moment Baltic officials had their own political motivation to smear Trump.
“Last April, the CIA director was shown intelligence that worried him. It was -- allegedly -- a tape recording of a conversation about money from the Kremlin going into the US presidential campaign. It was passed to the US by an intelligence agency of one of the Baltic States,” reported the BBC’s Paul Wood.
Is it just a coincidence that Brennan got this tape recording from a Baltic State intelligence agency in April when officials in the Baltic States were up in arms over candidate Trump? Recall that in March of 2016 -- the month before Brennan allegedly got the recording from Baltic spies -- Trump made remarks about NATO that the press was hyping as hostile to the Baltic States. [snip]
Hillary and her allies in the media seized on these remarks and ripped Trump on the false claim that, if elected, he would “pull out of NATO,” leaving Latvia, Lithuania, and Estonia to fend for themselves against Russia.
Such fearmongering set off an anti-Trump panic in political circles within the Baltic States. Out of it came a steady stream of stories with headlines such as: “Baltic States Fearful of Trump’s Nato Views” and “Estonian Prez Appears to Push Back on Trump’s NATO Comments.”
[Snip]
Both Brennan and officials in the Baltic States had strong incentives to help Hillary and hurt Trump. That Brennan and some Baltic spies teamed up to inflate the significance of some half-baked intelligence from a recording isn’t surprising. Only in such a feverish partisan milieu would basic questions go unasked, such as: Is it really a good idea to investigate a political opponent on the basis of a lead provided by a country that wants to see him lose?
Flynn
Flynn was Obama’s head of the DIA (Defense Intelligence Agency) and served only days under Trump. Reports this week initially made it appear that he was under investigation for ties to Russia, but it is more obvious to me that he knows about skullduggery by the prior administration in the Middle East, most likely Iran, and wants protection against the sort of unwarranted prosecutions Ted Stevens and Lewis Libby suffered at the hands of vindictive Democrats and their minions. The charges against him are being leveled by former Obama aide Sally Yates, who has utterly discredited herself earlier by her demonstrably false claim that the White House blocked her from testifying to Congress when the documentation clearly shows she was not. 
Perhaps the easiest thing to do is to just consider everything the Democrats say, directly or through the media, which just prints as truth handouts from the same Democratic sources, as a lie. You’d save a lot of time and most likely be right.