the key assumption here is *IF* LEDs actually give the promised lifetime. In my experience CFs never did (and incandescents seem to go much longer than estimated). At $10 an LED... I am absolutely willing to make that bet. At $20... I hesitate. I know I am timing the market. I know that's dumb.
Sure - there's a lot of uncertainty about whether the bulbs will make it to 25,000 hrs (I've heard some engineers claim they'll last far longer, and 25k is just the 'testable limit' right now)
The chip itself will last basically forever. It can run for hundreds, theoretically even thousands of years and still work.
However, two points to consider: It does degrade over time. The quoted numbers on the packaging is usually when the LED will reach 2/3 of the light emitted when you bought it - meaning a 800 Lumen lamp will have 530 Lumen after 15,000h -, not when it will stop working. But it will get less bright over the years or decades.
Second point: The really limiting factor - as with most things nowadays - is the electronic parts. You do have quite a number of soldered circuits, capacitors and control chips in every LED you buy. And these very likely will not last 100 years. Or even 25. Heat will degrade them more quickly (same with the LED chip itself), which is why LEDs are usually not recommended for closed environments where heat can't dissipate easily - The lights will last quite some time, probably longer than most incandescent bulbs, but they will not last anywhere as long as a LED that gets cooling or is used in a cold environment.
In my experience LEDs do last quite long. My oldest ones are now about 7 years old, still working fine (but technology moves on and they aren't as good as those you get today: they take a1-1.5s to light up, the CRI is lower, they are less efficient than modern LEDs and cost 30-40 € back then compared to 10-20 € for modern, superior ones). Of about 40 LEDs I bought over the years every single one still works - many no longer in my home, as I gift older ones I no longer use to friends and family.