[b]DISCLAIMER:[/b] I am not a professional player; the ideas I have might (and probably will) be flawed. Also, not all ideas are mine. I've seen some floating around and gathered ones I liked. All I want is to find a way to rework Pyro, to make the class have some use and I believe that TF2's competitive players are the best suited people to discuss balance/rework changes with. In other words, I'll be providing some food for thought in this thread (Please don't hurt me :( )

Another note: Pyro is supposed to be an Offensive class (according to TF2 class selection menu). I know quite a lot of people think it would be better to move Pyro to Support category. However, here I am focusing on Pyro as an Offensive class.
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[b]Pyro:[/b]
[list]
[*]Pyro's move speed increased from 300 to 345 HU/s (100% --> 115%);
[*]Pyro's jump height increased by 25-50%;
[*]Afterburn from different sources now stack (duration is not refreshed);
[*]Afterburn duration decreased from 10 to 5 seconds;

[i]Reasoning:[/i] Pyro is the slowest offensive class of the 3. Increasing it's movespeed emphasizes Pyro's offensive aspect. Jump height [b]could[/b] also be increased, so that Pyro would have easier time getting closer to it's targets when air-strafing through projectile spam. (Jump height by no means should be higher than Scout's double jump)
Besides that, afterburn from different sources stack, but is not refreshed by the added stack. This means that hitting target with Flamethrower, Flare and Sharpened Volcano Fragment will deal 3x afterburn damage but only for 5 seconds.

|-------PRIMARY WEAPONS-------|

[*]Flamethrower: (following changes apply to all flamethrowers, unless said otherwise)[list]
[*]Primary fire:[list]
[*]Reworked: now sprays a slim high-velocity-projectile stream of fire in a slight arc;
[*]Fired flames decay in 1-2 seconds;
[*]Increased point blank and short range damage by 20%/10% accordingly;
[*]Decreased medium and long range damage by 30%/40% accordingly;
[/list]
[*]Alternate fire:[list]
[*]No longer reflects projectiles;
[*]No longer disrupts enemy unit movement;
[/list]
[/list]

[i]Reasoning:[/i] Flamethrower now requires proper aiming and a bit of prediction when firing. The best examples of what I have in mind are [url=https://youtu.be/gliZe_Ddk7A?t=100]Killing Floor's Flamethrower[/url] and [url=https://youtu.be/DJ5yKtJeRic?t=140]Killing Floor 2's Microwave Gun[/url] (both without the recoil). Or you can imagine spraying gasoline through a slim water whose where gasoline is lit on fire while leaving the whose. You should get the idea.
Also, flames now last for a bit after firing if it does not hit a target. Like, you could spray the ground and for about 1-1.5 sec it would decay, while setting enemies, who pass through it, on fire for ~3 seconds. Flames who are in the air also decay in 1-2 seconds so that it could not be fired throught the whole map and randomly set players on fire.
Damage should be balanced in a way so that Pyro would deal a lot of damage from close range, but very little damage for further ranges (maybe even just setting targets on afterburn, no direct damage).
Finally, airblast is reworked to only extinguish teammates.

[*]Degreaser:[list]
[*]Airblast and switch speed numbers reverted to pre-Tough Break state;
[*]Afterburn removed;
[*]Airblast retains current airblast cappabilities (reflecting projectiles and disrupting/controlling enemy movement besides extinguishing teammates);
[*]Reflected projectiles no longer deal mini-crit damage;
[/list]

[i]Reasoning:[/i] Degreaser is now mainly an airblast weapon. It still has combo potential, but it is weakened, since targets cannot be set on fire. However, it's the only Pyro weapon which still can reflect projectiles and deny Ubers, so it will/should have it's uses.

[*]Phlogistinator:[list]
[*]Primary fire:[list]
[*]Reworked: now fires a slim medium-range hitscan beam;
[/list]
[/list]

[i]Reasoning:[/i] Basically made into Quake's Lightning Gun with no teammate extinguish capability and no long range potential (unlike 2 second decay flame projectiles).

|-------SECONDARY WEAPONS-------|

[*]Shotgun:[list]
[*]Now sets hit enemies on fire;
[/list]

[i]Reasoning:[/i] Now useful for afterburn damage stacking and could be used in combo with Degreaser to set targets on fire before hitting them with Axtinguisher.

[*]Reserve Shooter:[list]
[*]No longer a Pyro unlock;
[/list]

[i]Reasoning:[/i] In my opinion, it was never supposed to be a Pyro weapon. Also, being both Soldier and Pyro weapon makes it very hard to balance.

|-------MELEE WEAPONS-------|

[*]Fire Axe:[list]
[*]Added attribute: [b]Skullcracker[/b] - Cappable of headshots (all other Pyro melee weapons also get this attribute, unless stated otherwise)
[/list]

[i]Reasoning:[/i] Pyro is supposed to be more of a close range specialist/flanker, so that's a somewhat useful attribute to it's melee weapons.
On another note, melee weapon hit registration could be improved if such attribute would be added.

[*]Axtinguisher:[list]
[*]Reverted to pre-Love & War state;
[*]Does not have the Skullcracker ability;
[/list]

[i]Reasoning:[/i] Now that only Degreaser retains old airblast, Axtinguisher combo requires more effort, since you have to hit enemy with your secondary first.

[*]Powerjack:[list]
[*]Bonus movement speed when active reduced from 15% to 10%;
[*]On kill health restored increased from 25 to 50;
[*]Switch-to speed increased by 10%;
[*]Increased damage vulnerability while active from 20% to 35%
[/list]

[i]Reasoning:[/i] Since Pyro's base movement speed was increased, Powerjack's bonus was decreased. Also, somewhat increased weapons risk-reward ratio.
[/list]

|-------OTHER RANDOM IDEAS-------|

[b]Medic[/b]
[list]
[*]Can no longer be overhealed;
[*]Ubercharge build rate now has a modifier: (Standart rate) [b]/ (Number of medics in the team) (<-- added modifier)[/b];
[/list]

[b]Demoman[/b]
[*]Demomen of the same team now share the same placed Stickybomb counter;
[*]Maximum laid bomb amount is determined by team's Demomen Stickybomb Launcher with the lowest bomb counter;
[list]
[*]Quickiebomb Launcher:[list]
[*]Maximum laid bomb amount reduced from 8 to 4;
[/list]
[/list]

[i]Reasoning:[/i] These two last changes are ideas to make certain class stacking worse, yet still viable. This way, class limits might not be required (although at the current state they should be implemented). Also, these changes probably should only be implemented in competitive match system.

|-----------------------------------|

And that is it! Keep in mind that these are just some ideas I've seen floating around. I've gathered them, added some of my own and made this post to provoke the masterminds of this community. Come over here and share YOUR ideas!
In the end, the point of this discussion is to (possibly) guide Valve, show them ideas how they can balance the game.