I found a better source for the 2020 figure… Disney’s official SEC filings for Q4 FY2013:
https://www.sec.gov/Archives/edgar/data/1001039/000100103913000164/fy2013_q4x10k.htm
“Prior to the Company’s acquisition, Lucasfilm produced six Star Wars films (Episodes 1 through 6). Lucasfilm retained the rights to consumer products related to all of the films and the rights related to television and electronic distribution formats for all of the films, with the exception of the rights for Episode 4, which are owned by a third-party studio. All of the films are distributed by a third-party studio in the theatrical and home video markets. The theatrical and home video distribution rights for these films revert back to Lucasfilm in May 2020 with the exception of Episode 4, for which these distribution rights are retained in perpetuity by the third-party studio.”
Well, THAT’S definitive. I’m sure Disney will work out something to include IV with any movie set, but I’m sure the accountants will want to wait until May 2020 to ONLY worry about IV.