The terms of the settlement has been agreed to in principle. That means that whatever the sticking points that both sides could not previously agree to has been settled. The lawyers will have to work out the details.
Until there is a signed agreement, there is a possibility, albeit very remote, that the court case could resume and that would mean that MJ would have to go over to the UK to testify as he was originally scheduled to do.
I should also add that in a civil lawsuit, both sides can settle out of court at any time before a judge makes a ruling. Most of the time, cases are settled before the trial starts. What I suspect here is that the Prince thought that MJ would caved and settle before hand.
Those days for MJ are SO OVER. He ani't doing that shyt no more. And while I'm sure that he did not want to travel to the UK to have to testify, he was willing to do it to protect the rights to control his entertainment name and career.