If you've got a U.S. citizen or permanent resident relative within the U.S., that relative may well be able to sponsor you for permanent residence through the family-based process. E-2 nonimmigrant can, with the warning regarding adjustment of status discussed above, bear this process. Their employment or investment is determinative of their qualifications.
Thanks to the allowance of dual intent for E-2 applicants, if a relative files an immigrant visa petition for you, you would like not worry about losing your E-2 status. As an E-2 nonimmigrant, you'll even be sponsored by a U.S. employer for permanent residence. Dual intent principle will enable you to stay within the U.S. as an E-2 while your prospective employer navigates through the petition process.