I'm not talking about how Oda is treating Sommers during his fight against Zoro, where he is making Sommers look ridiculous and dumb.
When I say Sommers was a fun villain, I'm talking about before his fight against Zoro.
Unless you think the next arc after Elbaf is the final arc, then sure Blackbeard Pirates will be the final villain.
But I doubt the next arc is the final arc, so I highly doubt the Blackbeard Pirates are the last villains.
Also Zoro and Sanji could still fight Nusjuro and Ju Peter, going from Holy Knights to Elders makes sense.
And finally why introduce one of the Elders as a Swordman with the Shodai Kitetsu, if he is not going to fight Zoro.
Don't let Oda's treatment of Sommers vs Zoro, suddenly make you change your opinion on the Elders fight.
As for Killingham, no offense but if you think he will be more impressive than Sommers, you might end up being for a rude awakening.
The man was already off screen by pre CoC Sanji before, and was already kicked by Sanji in the last chapter.
It would be nice to see him getting some respect in a fight unlike with Sommers, but I doubt it.