A joystick wasn't my first thought for a product named Thrustmaster T16000

my main concern is keeping dust from collecting in the ball joint of the stick and the rail of the thrust slider

If your concern is the device failing, rather than making it look pristine when you're playing, unless you've got some specific reason to believe that it's going to be a problem, I wouldn't worry.

• I don't have that particular product, but I do have another HOTAS setup and pedals, which have gotten pretty dusty, and dust hasn't ever caused a noticeable effect.

• I haven't heard of dust being an issue for joysticks in general over the years, or for the -- even more common today -- thumbsticks, which are gonna have the same potentiometers in 'em and probably have a player applying less torque. Joysticks have been around for a long time, and using a dust cover hasn't been the norm. I've seen plenty of joysticks with all sorts of glop on 'em -- arcade joysticks would have people spill drinks and all sorts of stuff on them, and I don't believe that they're generally an issue.

• You can probably just vacuum them periodically and if you actually hit physical issues, can presumably open them up and clean the thing out. I'd guess that your computer's cooling system is probably more-impacted by dust than anything else in the environment.

• That dust cover is $40. That HOTAS setup is $170. Unless you think that dust is going to knock off a quarter the life of the thing or you are very, very particular about that particular HOTAS setup, it'd make more sense to just buy a new HOTAS setup when it fails, which would also provide an upgrade to then-current technology and be a fix for anything else that dies, like a cord being damaged or whatever.