From It’s All Part of God’s Plan:
Have you ever heard someone tell another who is going through a nasty life circumstance that “It’s all a part of God’s grand plan?” If that theory were even true, I don’t see how it would be comforting. I don’t see how the theory would make God out to be more trustworthy than if nasty circumstances were not in God’s plan!
[Quote of Exodus 5:1-6:1]
The above (rather lengthy) reading reinforces in the Book of Exodus the great need the Israelites had for deliverance. The people’s suffering, as emphasized by the additional suffering imposed in this chapter, was never God’s will. God did not want this situation at all (cf. Exodus 3:7; Isaiah 30:1; Hosea 8:4)! God, beginning here, worked through Moses and Aaron to turn the difficult situation into a powerful deliverance.
God is Open 
I do have one question. When God tells Abraham that his people would be held captive for four hundred years, how does open theism respond to this? Does God ensure that this will happen? I have almost come to adopt open theism. Prophecy still messes with me, and situations like the Israelites captivity and Peter’s foretold martyrdom are some of the things that still trip me up. Are there any tips and/or suggestions in helping me? Thanks.
Here is the question, is it 400 years or 430 years? Often with these timeframe prophecies the dates are given some leeway. The fact that these timeframes are not exact give evidence for Open Theism. How long would the Babylonian exile be?
https://godisopen.com/2016/04/21/loose-prophecy-dates/
So how does God know that this will happen? Does He ensure that it happens or is it a conditional prophecy?
Most prophecy is made in order to be subverted. I’m linking the Morrell chart on types of prophecy. It seems the 400 year prophecy had two purposes: to delay giving the promised land until the wickedness of the inhabitants justified explosion, and to protect fledgling Israel in the mean time. I would think that God, knowing the nature of Egypt, used them as a tool to fulfill His wishes. We don’t actually see oppression until a Pharaoh arises who does not know Joseph. Conceptually, Israel never had to be fated to be servants.
https://godisopen.com/2014/02/22/morrells-chart-of-prophecy-types/