Well Stackpole has said Tycho was in the A Wing behind Wedge when Wedge leaves the second Death Star so he should still exsist. But should disney really copy everything from the old EU? I would much prefer them to create their own characters and storylines. As you said they would change things and make characters different, as the Disneyverse has a different tone from the old EU. But why there are no new books with them there are still Rouge Squadron Fanfics which are written.