Even if he still knows how to do it, it's use would be extremely limited for him. Without the bijuu his chakra capacity will be massively limited compared to what it was before. Unless he's taken the time to master a lot of good "normal" ninja techniques these last 3 years he's still not going to be that strong because trying to use his old sand tech's isn't going to be chakra efficient. Especially not against an Akatsuki. Hell no one so far has been strong enough to truly kill a member of that organization. Gaara got whooped by Deidara when he had a bijuu, then later Chiyo says Sasori let them kill him, and in the end Deidara held back all of Team Gai with no arms and exploded himself. I really just can't see Gaara being a large factor in the fight after this.