SPOILERS AHEAD! READ AT YOUR OWN RISK!
Random Talking Bush on Spriters-Resource.com has ripped the newest Hyrule Warriors ingame portraits and also found placeholders for the future DLC characters in the process. That's what they say:
I was actually planning on doing additional DLC expectations for the two upcoming packs, but this will kill some of the fun. The characters of the A Link Between Worlds pack aren't really surprising, the Phantom Hourglass + Spirit Tracks character is, however, because I was 90% sure that it's going to be Linebeck. He appears in both games after all and he would make an interesting candidate, where he gets the Telescope as his weapon type, similar to his outfit in Tri Force Heroes - Aryl's Telescope could even be one of the tiers. And as part of his moveset he would summon his boat, throw around treasure and do other crazy things.
Linebeck would also look good next to Marin, because both characters got a wish granted from some giant whale in a dream world. The ending of Phantom Hourglass was very reminiscent of the one from Link's Awakening, where Linebeck essentially took Marin's spot... Anyway, this seems to be off the table for now and we got someone else instead, arguably not less important.