1– Oda is building the antagonism between the Revolutionary Army and Blackbeard since Dressrosa. In Dressrosa, Sabo, who is also the no. 2 of the Revolutionary Army, seized the Mera Mera no Mi and defeated Burgess. Later Burgess has infiltrated the Revolutionary HQ.
We know from the newspapers that Blackbeard and his crew attacked and destroyed Baltigo.
Finally the Revolutionary Commanders of the 4 Blues entered the scene by beating a subordinate of Blackbeard. This antagonism will necessarily lead to something.
2– We know that something happened to Sabo during the Reverie and in chapter 956 Blackbeard talked about getting something before the Navy.
Blackbeard’s reaction is included in the series of reactions regarding the Alabasta incident and the fate of Sabo (not the series of reactions regarding the abolition of the schishibukai) which suggests that the thing that Blackbeard wants is something related with Alabasta or with Sabo. Chances are that this is the Mera Mera no Mi that Blackbeard wanted to obtain during the Dressrosa arc.
3– On the color page of Chapter 987, Luffy carries a pipe, the weapon he used as a child but also the one Sabo still uses. On the other hand he wears a black shirt adorned with fruits which closely look like the fruit of darkness, the devil fruit of Blackbeard.
It’s possible that this foreshadowes a future meeting and possible clash between Blackbeard and Sabo.
4– The Mera mera no mi might not be the only fruit that interests Blackbeard among those in the Revolutionary Army’s possession. Blackbeard indeed seems to be interested not only in powerful Devil Fruits but also in Devil fruits made for espionage and infiltration.