I talked to a friend of mine over at the FCC about your questions, and he had this to say:
We asked the FCC:
* Why it feels unable to say the number of mobile operators that have broken the law
Because it's all of them, and that's super awkward.
* What steps remain for the sale of location data to be deemed an actual violation – as opposed to an “apparent violation” – and who makes that determination
Determination is made by Idjit Pie himself, of course, and no steps remain--it ain't happening.
Whether the FCC investigation has been completed or if it waiting on feedback from the mobile operators
* If be "feedback," you mean "the check," then they're still waiting, but hopefully not for long.
What the precedents are for similar violations
* There are no known precedents of a corrupt band of mafiya thugs holding the White House . . .
Whether there will be a fine and how it will be calculated
* If by "fine," you mean "campaign donation to the President," yes, and it depends on how willing the CEOs are to kiss orange gibbony ass.
Whether other measures will be considered against the mobile operators
The providers have to pinky swear that they won't do it again or they'll be on Double Secret Probation. Spankings may be involved--but wait, I've said too much.