I know it's kind of hard for P&N regulars to put two and two together and all, but this article should clear things up a bit.
Bottom line is that the FBI failed to vet any of its information and sources.  Steele lied to them, and because of their lack of attention to their sources, it wound up causing the FBI to misrepresent their warrant to the FISC.
On top of that, Bruce Ohr was feeding information to the FBI from his wife who worked for Fusion GPS.  That information was also coming from Steele.
This means the warrant is essentially illegal.  What the FBI presented to the court as three separate sources, was actually just one source, which was not vetted.  James Comey and Andrew 'Andy' McCabe signed the documents asserting the veracity of information being given to the FISC to justify the warrants.
I find it disingenuous to think that the FBI would not vet its sources to spy on someone associated with a presidential campaign, unless they thought the FISA 'secret' court documents would never be revealed.  If they failed to do that in this case, it was intentional.
That will probably kill the entire case, Page will probably win a civil suit, and Flynn's case will probably get dismissed.
Think not?  From 
The Hill : "Ohr’s failure to notify the Department of Justice at any point about his and his wife’s relationships with the target of a congressional investigation and possibly a target of a Department of Justice investigation compares to one of the issues Mueller’s team used to get Michael Flynn to plead guilty: a failure to disclose meetings and relationships to federal authorities."
So on the back of all this, perhaps this makes more sense :
Mueller team seeks delay in Flynn sentencing
Now, if you want to dig further, look at who Natalia Veselnitskaya is, who does she work for?  That's right, a law firm working for Fusion GPS.  
Fusion GPS was paid by a law firm for work on behalf of a Kremlin-linked oligarch while paying former British spy Christopher Steele
Now this is my speculation, but I think it's pretty clear what happened.  Fusion GPS was being funded by a Russian oligarch, and was used to feed the Trump Dossier to the DNC/Hillary campaign.  At the same time, they tried to feed information to Trump on Hillary.
Guess which one bought it, and which one didn't?  Which side colluded with Russia again?
https://www.washingtontimes.com/news/2018/feb/7/christopher-steeles-trump-dossier-info-led-fbi-mis/