We are still only on playable day 12 of 30 and have had just 1 of, I believe, 4 or 5 events on this Dylan/Ellie side story, so there is a long way to go and more than enough time to build something between them in a way that works and makes sense (hopefully moreso than Dylan's dumbass blackmail shit).
I honestly do think it will lead to that just as I believe that there will be action between all sorts of different combinations of the family members (Liam excluded); Sophia/Ellie, Sophia/Dylan, Sophia/Patricia, Ellie/Dylan, Ellie/Patricia, Dylan/Patricia, Sophia/Ellie/Dylan, Sophia/Ellie/Patricia, Sophia/Dylan/Patricia, Sophia/Ellie/Dylan/Patricia.
Them going off alone to some secluded spot for some sisterly "brokebacking" would be very nice.