People really thought Oda allocating five currently active devil fruits in a SBS question to Zoro, Nami, Usopp, Sanji and Franky was just going to be nothing. It seems likely Blackbeard will be around long enough to see at least one of these does happen. My guess is Nami eating Enel's fruit is most likely, then Zoro's sword eating Kaidou's fruit and lastly Usopp.
Hancock doesn't really need a fruit to be able to join the crew. She already has a higher bounty than Zoro and better CoC. Hanock losing her devil fruit pretty much confirms she joins Luffy's crew. Hurrah! Hancock turning Devon to stone pretty much sets up a revenge match for when Luffy's crew faces off against BB's crew.
So assuming Blackbeard wants Hancock's fruit for himself, would this mean the Mero Mero fruit is actually a mythical Zoan? Perhaps it was Rocks D. Xebec's fruit.