I think the supposedly already-past lifespan of ten thousand years is more problematic than the prophesied one. No reason to assume this isn't just a metaphorical story, as Tilt said, encouraging a king to be wise.
Gain and loss, status and disgrace,
censure and praise, pleasure and pain:
these conditions among human beings are inconstant,
impermanent, subject to change.
Knowing this, the wise person, mindful,
ponders these changing conditions.
Desirable things don’t charm the mind,
undesirable ones bring no resistance.
His welcoming and rebelling are scattered,
gone to their end,
do not exist.
- Lokavipatti Sutta