If you look at scientists hundreds of years ago, you'd say they didn't know very much about their world. And back then, they thought their predecessors were ignorant.
There is no reason to believe that in a hundred years, people will look back at today's scientists and think that we were very ignorant.
If anything I would say that the rate of knowledge acquisition is increasing...therefore the knowledge gap between now and 100 years from now will be significantly greater than the knowledge gap between 100 years ago and now. So while they probably won't look back and think we are ignorant, they probably will look back and laugh and many of our crazy ideas and question how we couldn't understand things that are "a given" in 100 years time.