"I'll be" is the contraction of "I will be" or "I shall be", used for future states, plans, or promises. It signals intent, prediction, or readiness, often before a place, time, role, or adjective.
I never forget a face, but in your case I'll be glad to make an exception. Groucho Marx
What will I be doing in twenty years' time? I'll be dead, darling! Are you crazy? Freddie Mercury
I'll be damned if I am not getting tired of this. It seems to be the profession of a President simply to hear other people talk. William Howard Taft
If neurotic is wanting two mutually exclusive things at one and the same time, then I'm neurotic as hell. I'll be flying back and forth between one mutually exclusive thing and another for the rest of my days. Sylvia Plath
I'll be more enthusiastic about encouraging thinking outside the box when there's evidence of any thinking going on inside it. Terry Pratchett
Ye'll be hang'd and I'll be harried. English Proverb