They'll likely replace the sentry gun with a oil pump, meaning the Texan Engie can merely sell out the other team.
Still, cant be as bad as that sodding bow and arrow.
actually that's not a bad idea. It works form a thematic standpoint. Texan. Engineer. Oil.
Imagine if they replaced the sentry gun with an oil slick generator. Pyros could set the oil on fire.. wouldn't have any real range, it would basically just squirt oil at a specific spot, like a chokepoint.
It would be difficult to see unless you were looking down for it (it might just give the ground a different sheen, like that purple greeny sheen you get on something covered in gasoline). Then a pyro can light it in a pinch, and it will burn briefly, go out, and a new batch of oil will be splurted out.
When not lit, it could give a sort of "intoxicated" blur effect from the fumes to people who are walking over it.
It would definitely change the dynamics of who beats engineer - as of right now, it's spies... spies beat engies.. sneak past, zap their shit. It would change it to Pyros beating Engies, at least Engies that use the Oil/Gas Pump. Pyros can run right through the flaming gas without catching fire. and decimate what's on the other side - the reason Pyro's don't already kick engies asses is because of the sentry.. they're useless against them. It also would also help engies specifically against spies, as the fire would thwart them sneaking in unseen.
Also, for kicks, you could make it so the Pyro's Hadouken Taunt and the Spy's Cigarette Taunt both light the gas. Would make for a pretty awesome "Meet The" video.
Meet the Gas Pump
RED Engineer: Hey, Spy, checkout this awesome new rig I set up. I set it up so it would pump gasoline all over the ground there.
*pump squirts gas all over a hallway*
RED Engineer: All we need now is a little fire to light this badboy up!
RED Spy: Oui Monsieur..
*Takes a drag on his cigarette and throws it into the hallway. Screaming is heard, and BLU Spy rushes in on fire. RED Engineer and RED Spy laugh and Guffaw*
*A muffled yell is heard as BLU Pyro bursts through the flames relatively unharmed*
RED Spy: Merde.