Do Most LED Hallway Lighting Fixtures have replaceable lamps
Time for math!  I love math.

50,000 hours x 25W x $0.12/kWh = $150 total running costs over the lifetime of the LED fixture.  Plus the cost of the unit itself - say another $150.  That's $300/fixture, or $60/fixture-year.

By contrast, a halogen bulb costs $2.50 and lasts 1000 hours.  So you need to buy 50 of them to meet the lifetime of the LED bulb.  That's $125 in bulbs.  Plus running costs: 50,000 hours x 72W x $0.12/kWh = $432 in electricity.  Neglecting the cost of the fixture, as it doesn't get replaced, you're spending $111.40/fixture-year for something that has the benefit of being replaceable.

A CFL equivalent might be $4.50, so it's more expensive than the halogen, but it also lasts longer (10,000 hours-ish).  It also uses less power than the halogen, but more than the LED.  Using the same math, you'll spend $45 in bulbs and $132 in electricity, for an average of $35.40/fixture-year.  So if you're going to go replaceable bulbs, definitely go CFL (but then you have to live with the light of CFLs, which some find objectionable).

TL; DR: Even replacing the fixture every 5 years, LEDs are cheaper in the long run than halogens.  CFLs are even cheaper than LEDs (slightly less efficient, but cheaper bulbs), but their light is objectionable to some.