... Basically, it all went a bit off-script due to unforeseen technological advancements (namely ASICs) and now we're making the best of a less-than-ideal situation. Perhaps it does raise questions over Bitcoin's longevity, but it's likely we'll find a solution later down the line.
Are ASICs really an unforeseen technological advancement? ASICs have been used in other industries for years and obviously
make sense in situations where efficiency on a single task is more important than being
good at many different tasks.
If I recall it correctly Satoshi also predicted that mining would become very competitive and that
eventually CPU mining would become obsolete. Regarding the actual topic I think BTC will thrive even
when the block reward hits zero. Transaction fees will be extremely high by then and BTC will be used mainly
for big transactions. Expressed in $ fees will likely be a multiple of the fees today, but as a percentage of the
BTC price they will still be pretty cheap.