The way I see it, we're headed towards one in all but name. Treaties are basically the sharing of laws at the end of the day, sure we negotiate them as financial reasoning, but they usually end up leading to laws such as forcing the DMCA or the Kyoto Protocol that require member governments to conform to certain standards, almost always those standards are done via law. We can say these are being done in mutual interest, but at some point we will be a group of countries following a standard set of laws, I'm not saying anytime soon or that there won't be resistance, but one day it's a vast possibility. Instead of indefinite treaties we should use mutual agreements for set periods, at the end renegotiate them. Of course this could just be the ramblings of a mad man who has no clue. Also this doesn't necessarily mean a one world government.