Well, the engineer is one of the most balanced classes.
In my opinion, players are looking forward to:
1. Smoke grenades for everyone (as a countermeasure against casual sniping, and a more convenient rush for positions, avoiding fire from multiple enemies during unbalanced gunfights)
2. Removing the spot-sweeping mechanic, and generally increasing the TTK (again, it will be easier for the engineer if gunfights are fairer and console players won't wipe him for 0.2 seconds)
3. It would be cool if mines worked on light vehicles again. (I don't quite understand why jeeps were given immunity; it's super cool if they want to crush you, and you, as an engineer, throw a mine under yourself and jump to the side, blowing up the jeep.)
4. You wrote that you'll increase the minimap scale for aircraft, and that's good. But what about the ability to increase the minimap size on the screen even more?
+ Often, when playing as an engineer and throwing a mine, you see it on the minimap. But if you move far away, it should still be visible on the minimap, but it simply disappears until you approach (at a large minimap scale). It's as if objects simply have a limit on how far they can be drawn on the minimap; it would be cool if there was no limit.
PS: A couple more things regarding usability.
a) The ability to assign separate keys to ping and common rose. Often, when trying to ping, a rose appears and you get killed.
b) When driving a vehicle, PC players are forced to fight the camera. You turn sideways and the camera follows you, you drive over bumps and it bounces up and down. There needs to be an option to disable camera aiming assistance in vehicles while moving. This feature is enabled by default for console players; PC players don't need camera assist; we have a mouse. Right now, it seriously interferes with visibility.