I agree with Yeef, the only issue is that Valve has pretty much given up on buffs and have made the Pyro class a combination of powerful mix and match weapons.
For example, the Degreaser was practically a straight upgrade. If they wanted to really differentiate it from the flamethrower, the stats should be:
Flamethrower
+25% airblast cost (so it's now back to 25 ammo per airblast)
Degreaser
-10% damage
-25% or maybe even -50% afterburn damage.
That would have solidified its role as an airblast machine that is also designed for quickswitch shenanigans. Or even swap the airblast cost with the regular flamethrower (make it 25) so you know the point of the weapon is switching to your secondary/melee and the regular flamethrower is best for airblasting.
The other issue is that no class has to switch weapons as much as a Pyro. Just about any of us can jump onto a Valve server, pick any other class, and with only the primary weapon and access to right click score much better than you would as a Pyro in the same situation (for the purposes of this argument, the knife, the medigun, and the sticky bomb launcher are considered the primaries, but you could probably score better using only the Enforcer, Blut, and Pipe launcher anyway).
So, the Pyro is now a bag of tricks. Even the demoknight paired with a grenade launcher feels more solid and cohesive to me.
The only other buff they could give the Pyro now would just be a flat buff to his weapon switch. Give him something like +20% faster weapon switch on all weapons and nerf the Degreaser a little bit. Then he'll feel like a bag of tricks character from just vanilla play.