Thank you KittenKat..
Let me explain my scenario little more clearly.
My sponsor is wife. She just started working this year and makes above the poverty line. Since she did not have income in the last 3 years, the lawyer said, I can be on the I-864 form and use my income as part of the Household income and thus avoiding the scenario of co-sponsor.
So, my question is, since my income is part of the income requirements for I-864. What if I lose my job before my GC is approved. I hope I am clear enough about my question