Will All Attain Enlightenment?

In the Saccasaṁyutta there are a series of suttas (SN 56.61-131) on the rarity of the precious human birth, like how few are born as humans (SN 56.61; see also the blind turtle simile: SN 56.47-48), not in a borderland (SN 56.62), and with wisdom (SN 56.63), and among those passing away as humans many are reborn in the lower realms and few in the heavens (SN 56.102-107). On the other hand, attaining insight is supremely difficult (SN 56.45) but without it there is no liberation (SN 56.44). At the same time, speculating about various matters of the world is not beneficial for the path, rather one should get busy with understanding the Dharma (SN 56.41).

The Buddha was asked (AN 10.95): 'when Master Gotama teaches in this way, is the whole world saved, or half, or a third?'
And Ananda explained: 'it’s not the Realized One’s concern whether the whole world is saved by this, or half, or a third. But the Realized One knows that whoever is saved from the world—whether in the past, the future, or the present—all have given up the five hindrances, corruptions of the heart that weaken wisdom. They have firmly established their mind in the four kinds of mindfulness meditation. And they have truly developed the seven awakening factors. That’s how they’re saved from the world, in the past, future, or present.'