HODL works until it doesn't work and then you're screwed.
Exactly. Hodl'ing makes sense, sure. But for something like 100 years like the op is joking about, or even just a decade, it's impossible to know where bitcoin will end up. I don't think it's a good idea to hold until the end no matter what, especially if some altcoin comes out that improves on bitcoin. Blockchain technology will probably be here to stay, but bitcoin, everyone can be a little skeptical about. I think it'll be here for a while, but I just don't think it'll be a super long time.
Just imagine hodling for a certain number of years only to end up with nothing because the value has depreciated or crashed - then you're really screwed by then because you have wasted time and effort to keep the bitcoin for all that time. It's hard to know when the end is so I think hodling just for a certain period of time like 5 or 10 years is already ideal since you would surely gain some profits already by then.