I was wondering can HID bulbs lose their intensity or lumen output over time? Or is it the ballast that could cause the bulb to produce less lumens. I was under the impression that an HID bulb is on or off, and only those options. I didn't know they could wear and produce less light.

Yes the bulbs can lose output and change color over time, especially the aftermarket ones. OEM grade HID bulbs are rated for about 2500 hours which is a long time, but aftermarket bulbs can be a crapshoot.
A failing ballast will usually result in the bulb not lighting up at all or flickering.

the salts inside the bulb's chamber gets used everytime the bulb is ignited (turned on), so yes, they will "wear out" over time. you can see the most significant change in color after burn-in, or around 100 hours (philips 85122/6 bulb) of initial use of a brand new bulb.

Certainly a lot longer than halogens though, right?

Because driving with it on for 2 hours at a time would mean that after 50 days, the HID would need replacing?? That would mean I'd need to replace HID's every 6 months with the amount of night driving I do. Is 100 hours even established?

2500/2hr daily = 1250 days.

2500/2hr daily = 1250 days.

Oh sorry I meant 100 hours after burn-in... someone said something about significant color change after that time.

Hey rougeben83, how's that thing I sold/bought to/from you? I remember your name for some reason. PP6? STi springs? MRT headers? What did I purchase or sell?!? lol

Oh sorry I meant 100 hours after burn-in... someone said something about significant color change after that time.

Hey rougeben83, how's that thing I sold/bought to/from you? I remember your name for some reason. PP6? STi springs? MRT headers? What did I purchase or sell?!? lol

???
Does that mean the color/lumens change after 100 hours after usage? Mine i would guess only has a total of 20 hours usage at most.