So as it turns out, they managed to have Alec Guinness and Ewan share Obi Wan’s lines in the ‘vision’ sequence:
http://www.ew.com/article/2015/12/20/jj-abrams-reveals-obi-wan-and-yoda-are-star-wars-force-awakens
(Had to change his comment because I don’t know how to read articles)