Fujitora is trying to change the entire WG system from within, so odds are that the abolishment of the Shichibukai is just the big but crucial first step in his grand scheme.
My point is that not everyone needs to have run after the OP to have an ambition driving them forward, also in strength. Likewise will Akainu have a motivation for being the way he is, we just didn't get to that yet.
I'm referring to this from the SBS volume 76:
"Could the two new admirals "Ryokugyu" and "Fujitora" possibly have been created with the concept that, despite them being people of the Marines, deep down inside they are both Admirals who secretly harbor ill feelings towards the World Government (going against the WG → kind of like pirates?) as can be seen with Fujitora's wish to completely abolish the "Shichibukai" system set up by the World Government? P.N. Tosaka Kouhai"
"O: What? Me, becoming restless? (cold sweat) W-w-what are you talking about? Of course not.
Uhhh, well that was one heck of a complicated theory written on this piece of paper. If you want to, go ahead and try to process it. I haven't said a single thing about whether this theory is correct or incorrect, okay! (cold sweat) Just saying. I j-just happened to throw this postcard in, so that I could show my fans the kinds of questions I've been getting and s-stuff."
Oda basically admitting that, like Fuji, Ryokugyu has a secret ambition against the WG, so both Admirals will likely be the leaders of the new Marines in the future
.