Armstrong has been motivated his entire life by two things, money and public adulation. The reason he went in to cycling was money. He never had any respect for cycling's traditions. He never cared about the sport, ever. He never really liked the sport. It was always about money. Unless he has made disastrous financial decisions over the last decade then he does not have to worry about that motivation again, even with the potential lawsuits hanging over his head.
It is about having his ego stroked. He cannot stand that his pedestal has crumbled underneath him, that he's no longer idolized, and that people are referring to him as the Bernie Madoff of sports. He wants the respect back. That will shape his "confession." It will concentrate on casting him in the best possible light with a good layering of excuses for his behavior.
Any confession will be light on details and heavy on rhetoric about doing what "everyone else was doing". Do not expect him to apologize to all the people he bullied and whose lives he destroyed for daring to tell the truth about him because that won't be part of the narrative. He wants to be "the guy who had to go along to get along", not the guy who spread lies that a female employee was a prostitute, or the guy who hounded people out of jobs and blacklisted them so thoroughly that many of them had to literally move halfway across the world to start a new life because they refused to commit perjury to protect him.
Don't expect him to talk about bribing the UCI or having positive tests fixed or being protected by his buddies in government offices because, again, doing much much more than other riders is not the story he wants to tell the rubes.
Expect to hear a whole lot about cancer and how he needs to get back to helping people. Expect some shameless exploitation of his children as a reason for why he decided to come forward. Also expect complaints about being singled out and treated differently than his teammates who got six months.....even though he was offered the exact same 6-month-sentence-in-exchange-for-testimony deal as them but refused it.
The interesting thing will be whether the journalists who write articles after his appearance will buy what he is selling.