Koxinga dies earlier than IOTL and Taiwan remains a Dutch holding.
Then the main cause of Qing invasion disappears. Despite the initial clashes over Pescadores, the Dutch are not seen as much a threat as the kingdom founded by Ming loyalists on Formosa; for the Chineses, Formosa wasn't a land worth of being conquered.
The island becomes a place for barter trade with China, Dutch putting its lands into cultivation, producing many items to be exchanged with Chinese merchants, palliating the deficit of silver.
To cultivate the land, the Dutch would have brought in Han settlers from the mainland. This was a common practice before Koxinga conquest.
Then, there would be mestizos produced by marriage between Dutch, Aborigines and Han settlers.
Then, Aborigines' culture would be better conserved thanks to the Dutch missionaries which had begun to romanize their languages.