I think that Honoka's chances have been reduced, due to the fact that she was rejected once and while that hasn't made her give up ... the author isn't actually putting much development with her relationship with Tatsuya ... which is a little bad, if that is actually his intended final paring.
At the very least I don't remember a moment where she tries to understand Tatsuya better or deepen her relationship with him in some way.
While Miyuki gets plenty of moments regarding her relationship with Tatsuya, for example in volume 13 and the author can always go with the not blood related route - at least not as closely related as they currently are - since the single proof that has mentioned that Tatsuya and Miyuki are siblings was the DNA test from volume 5, which could have easily been fabricated by the Yotsuba if they wanted to keep some secrets hidden from the siblings past, which apart from the event from 3 years ago, we don't know a lot about.