That's a great question, and it's pretty fundamental.
The most important criterion for a peace plan to be credible is to get support from the parties to the conflict. We aren't there yet. If all Arab countries, the United States, the Europeans and the entire world commit to a peace plan as drawn up, it means that the whole world believes that it's possible to achieve that status and foster a climate with greater trust between the parties.
For the peace plan to be credible, the first elements of the plan have to be carried out. For that to happen, Hamas has to completely transfer power and be demilitarized. The civilian population also, of course, has to stop suffering.
That means it's absolutely essential for humanitarian aid, such as medicine, clean drinking water and staple foods, to be able to enter the Gaza Strip.
Once those elements are in place, there's a collective belief that mutual trust can begin to build between the various parties to the conflict.