This explosion around the FISA court is surprising to me, as I've known about this warrant since last year at least. Heat Street broke the story right before the election, which means the existence of the investigation was leaked in a blatant partisan attempt to sway the election. The existence of the server around which the warrant revolves had been reported in the press even earlier in the campaign
Nevertheless, there's an interpretation of this story in which no one -- except the leaker -- did anything wrong. On this interpretation, the FBI sought the warrant out of legitimate concerns, without political officers pressuring them in any way. The FISA court took the unusual step of rejecting the warrant until it was narrowed in scope precisely to avoid the kind of worries about wiretapping a political opponent that are now playing out. Though the Obama administration would of course have taken an interest in the findings, that is only because they had a duty not to hand the keys to a Russian agent (or a President under the influence of Russian agents). However, as no one on Team Trump was doing anything nefarious, the investigation came and went without anyone being charged.
On this interpretation, the pings from the Russian bank's server were part of the generalized Russian intelligence collection effort aimed at Team Trump -- an effort exactly similar to our CIA's efforts in France, and for the same legitimate purpose. While we have reason to contest Russia's intelligence collection efforts even where they have a legitimate purpose, in fairness we would have to say that Russian intelligence collection efforts aimed at understanding a candidate who might win the election represents a perfectly understandable interest.
So, there is at least one plausible interpretation in which no one has done anything wrong, except the leaker who decided to betray their oath to keep classified secrets for partisan political advantage.
Of course, there are also other interpretations. These run the gamut from the investigation into Trump being a purely political gambit aimed at using the national security state to destroy a political opponent -- similar to the IRS targeting scandal involving Lois Lerner -- to Trump or some of his close associates being spies in the service of Mother Russia.
In military intelligence, the MPECOA is the 'most probable enemy course of action.' Officers typically assess both that and what they take to be the 'MDECOA,' the 'most dangerous enemy course of action.' I have dropped the 'e' here because we are speaking of fellow Americans, both Team Trump and Team Obama.
I assess that the MPCOA is that something close to the 'everyone was legit' interpretation will prove to be true, and that the investigation that is likely to result from this will end up serving as a warning shot from Team Trump to Obama and his loyalists. Two can play at this game of using the national security state to delegitimize each other, and Team Trump controls all the actual levers of power. If that works out, we might see some backing-off on the constant leaks and attempts to delegitimize the Trump administration by Obama loyalists. That would work to the general benefit of everyone, even them, though they surely don't realize it. Still, the best thing for everyone would be for them to return to being a legitimate political opposition, and stop trying to overthrow the government through leaks and "narratives."
The MDCOA is that the investigation will turn up something that Team Trump can use to try to prosecute Obama loyalists, or worst of all, Obama himself. This is an extremely dangerous situation regardless of whether Obama deserves to be prosecuted or not. At that point the country will divide sharply, and turning back will be very difficult indeed. It could still be done -- Trump could magnanimously pardon Obama, and the two could shake hands and agree to respect one another henceforth. That isn't very likely, however. What is more likely is a heightened political division that would result in severe sheer stresses on the Republic.