Hello Omegatime, it seems like the Lord answers your question in the second half of v10 (which was not included in your OP).
Isaiah 46
9 “I am God, and there is no other;
I am God, and there is no one like Me,
10 Declaring the end from the beginning,
And from ancient times things which have not been done,
Saying, ‘My purpose will be established,
And I will accomplish all My good pleasure’”
What this passage tells us is that God is sovereign over everything, PTL, that He ordains whatsoever comes to pass (and that before any of it happens). What this means is that He is the One in control, because nothing happens in this world apart from His will and foreordination. This also means that nothing will ever be a surprise to Him .. because He has either 1. allowed it to happen or 2. caused it to happen .. or 3. stops it from ever happening.
This is also why we know that we can trust everything that He says to us, which certainly includes all of the great and wondrous promises that He's made to us in the Bible ).
God bless you!
~Deut
p.s. - here are a few examples that come to mind.
Psalm 33
11 The counsel of the LORD stands forever, the plans of His heart from generation to generation.
Romans 8
28 We know that God causes all things to work together for good to those who love God, to those who are called according to His purpose.
1 Corinthians 10
13 No temptation has overtaken you but such as is common to man; and God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will provide the way of escape also, so that you will be able to endure it.