It can be reasonably asserted that it was a relative certainty from the start of the universe that there would be organisms with eyes at some future point.
Oh? Why is that? Because light exists? For the same reason, we can be sure that a mass-sensitive organ will eventually exist, able to detect objects by the gravity the generate. Or even senses that we can't conceive? Like, oh, say "Smision"?
I don't see that eyes are any more certain than any other conceivable organ.