Yes it is always good to have a plan B. Plan B for us isnt not a contraceptive we can just take haha. Leaving the United States unless you were completely and totally undocumented(no record accept for academic and maybe medical, no biometrics at all on record) here will follow you forever and should you ever try to enter another country it will be an issue you will have to face and explain again, and many countries now days dont let visa over stays from other countries obtain visas because they fear your past history. Oh and btw if you are completely and totally undocumented you also have to leave under the radar, any U.S. presence of you will create an issue including crossing a border if they record you leaving.