The scenario of outright conquest seems unlikely because of the vast organization in a relatively short period of time that it would have taken. A fully-armed and organized mass invasion of what was to become their homeland by a returning Israelite force seems, even by modern standards of warfare, to be an arduous and gargantuan task. Would the returning Israelites have actually slaughtered anyone who got in their way? One would think God's chosen people would have shown more mercy than such a plan allows.

The idea of quiet infiltration makes sense on a small scale, but it has limitations. Such a plan would take decades and generations to actually affect change. Even after the passing of much time with infiltration, commerce, intermarrying, etc., what is the guarantee that the governing body would actually be impacted and would surrender and shift?

Putting down roots in the form of establishing commerce, choosing and maintaining a form of government, building an infrastructure of roads and sources of water, and protecting the new land from marauding bandits and angry former residents would take intelligent mobilization and socialization. A group that had been living in survival mode for some time would have needed to make a massive adjustment to prepare for prosperity in a promised, but still new, land.