CNAS has released a long report edited by Andrew Exum on how international forces might help solve the Israeli-Palestinian conflict. Lynch is one of the authors:
My concluding chapter sketches out four scenarios under which such an International Force might be deployed --- with or without the Palestinian Authority in its current form, and with or without a negotiated agreement.
The best case scenario of a full negotiated peace is complex enough, with many opportunities for spoiler attacks and with the job of enforcing compliance with the agreement creating endless opportunities for conflict and clashes. A partial agreement scenario, where Israel reaches a peace agreement only with the current PA in the West Bank, is one of the more likely scenarios and one of the most dangerous for an international force since there would be great pressure for it to morph into a counter-insurgency force battling Hamas and other opposition movements. The other two scenarios would follow from an Israeli decision to unilaterally disengage from the West Bank as Sharon did from Gaza, a move which the current PA might or might not survive. While no government may want to become involved in such a situation, they may do so as the only alternative to the PA's collapse.
There is much more there, and this overview can not do it justice. I hope that you'll read the whole thing and that it might help trigger productive debate on exactly how a two-state solution might be achieved should we ever get to that point.