Could anything have been done differently that might have prevented their community from falling apart?

Well when the white missionaries showed up it was pretty much game over for the tribe. Colonial situations like this litter Western history. The breakdown of their religion directly breaks down the structure of their society. It's not that their society was perfect, in fact it was unforgiving and often cruel. Still the disintegration of their belief system meant the end of Okonkwo's once proud society.