Here is a possible outcome of who could replace Ted DiBiase or join Legacy in the near future. Legacy only needs one more member, if it is possible.
Just seeing these three might be the answer everyone has been looking for. Whatever the outcome is, we will see who fulfills the description or replaces one or the other in the group.
As it seems, DH Smith was mostly speculated to be the next member of Legacy. Smith was drafted to ECW in the WWE draft, in order to team up with Tyson Kidd to form the New Hart Foundation. For the time being, I guess the plans for Smith joining Legacy has been put on hold.
I think that the point of DH Smith going to ECW was to build his career, so he could elevate just a bit then move on. Smith has potential no doubt he just has not been exposed to enough air time. Then Smith will have his chance to become a top star and champion.
As of now there seems to be no sign of Smith going to join, unless the WWE moves him to raw to be a part of Legacy.
Joe Hennig, the son of Mr. Perfect, Curt Hennig. Being a third-generation superstar, he is qualified to be in Legacy. Word in FCW is that Hennig is very good, and his performance is phenomenal. If the WWE does decide to add another member to the group, the Henning would fit "perfectly."
Hennig suffered a serious injury last month and could be out for a while. If Hennig heals in time, he may put in Legacy, if the WWE decides to do that. In this case, if not DH Smith then Hennig would be "perfect" for the Legacy and being by Orton's side.
Brett DiBiase is the youngest son of Ted DiBiase and younger brother of Ted DiBiase Jr. Also a third-generation wrestler, DiBiase would be probably the best replacement for Ted because the same family and the same last name makes perfect sense. Replace one DiBiase with another DiBiase.
I don't think Brett would join Legacy though. He just joined FCW in October and is only 21 years of age. So, he needs time to develop in ring skills and bulk up.
To my knowledge, I think either Joe Hennig will join or DH Smith will, if he debuts in ECW soon. Only time will tell us what Vince McMahon will do with the group.