You can use "I'll be ___" to tell how you're going to feel about something at a certain point in the future. Some examples are:

I'll be sad to see him go.

I'll be interested to see how effective that ends up being once everyone else catches on and starts to imitate them.

It's really common to use the words "glad when" together:

I 'll be glad when this is all over.

I 'll be glad when I'm done traveling.