Part of the ongoing Verse Quick Reference project.
Gen 11:6 And the LORD said, “Indeed the people are one and they all have one language, and this is what they begin to do; now nothing that they propose to do will be withheld from them.
The context of this verse is that the flood waters have subsided, humanity begins to multiply, and the people begin to defy God. God sees this happen and declares that “nothing that they propose to do will be withheld from them”. This is a criticism, and God then acts to confuse the languages to thwart the people’s actions.
The phrase “nothing that they propose to do will be withheld from them” applies to human beings. But if this statement were to be made in relation to Yahweh, all sorts of metaphysics would be imposed on it. For example, CARM uses a similar verse for omnipotence in God:
Psa 115:3 But our God is in heaven; He does whatever He pleases.
CARM writes:
Omnipotence is an attribute of God alone. It is the quality of having all power (Psalm 115:3). He can do all things that do not conflict with His holy nature. God has the power to do anything He wants to do. However, God cannot do that which is contrary to His nature. For example, God cannot lie (Titus 1:2).
This is an example of too much being made of too little.
God is Open 
This is also a clear example of God responding to man. He extrapolates what could happen if he doesn’t take action, and this takes action. He’s not seeing *the* future but a possible outcome within man.
Is this a failed prophesy? Did God make a mistake? “Nothing that they propose to do will be withheld from them.” Not so, since God took action. Apparently, God undermined his own prediction about man’s future.
The whole thing becomes a mess unless you take read the text as it’s intended: God is a personal God who can extrapolate what may or most certainly will happen. He simply explains his motives behind confusing the language, motives derived directly from a response to man.