im more concerned about the fact that despite SpecsLuke does hit common Luke counters hard, it is possible (and for some frequent) that multiple such counters exist. For example, we won't be surprised to see both gyarados and forretress on the same team. since only aura sphere covers both for potential OHKO or 2HKO (and for gyarados it might need a 3KO), it somehow leaves a dangerous gap for things like celebi to come in and set up. the presence of ghosts proves to be a problem too.
I agree. One attack gives away SpecsLuke, and its common for the Lucario swap in to not take much damage. This gives away the surprise of Specs. LO recoil means little due to 4x SR resist. SpecSLuke then gets beaten by prediction, as with all choice users, he doesn't have hard hitting moves (best is Aura Sphere, which is decent, but can be walled by the common Rotom, and Dark Pulse is much more easily walled).
SD Lucario is more frightening due to SD boost, Close Combat's 120 bp, and the ability to swap attacks, meaning more than prediction is needed to counter Lucario.
However, I suspect SD Lucario will drop in popularity because one of his biggest selling points was a hard hitting priority move. That role has largely been taken over by Scizor. SpecsLuke can make a comeback to combat some of Scizor's weaknesses, but there is no way he's getting past Gyara.
Oh, and Vacuum Wave > Psychic > Flash Cannon. Priotity moves are more important due to more Scarfers and priority moves. Flash Cannon has crap type coverage, and is almost always inferior to his other moves. Psychic hits Tentacruel, Heracross, Breloom and other Fighting and Poison Pokemon, but Vacuum Wave is usually better unless you have enough speed on your team.