It seems that the LTTE movement came about because the Sinhala were exploiting the Tamil, passing exclusionary laws meant to marginalize the Tamil, etc. I really doubt the Sinhala will make that mistake again. Prabhakaran really hated the Sinhala, and he was smart as a whip. He and Arafat invented modern terrorism out of nothing. And Arafat generally copied much of what Prabhakaran did.
Prabhakaran refused to surrender, even at the end when there was nowhere left to run he charged a roadblock evidently in a me-or-them mentality. The war dragged on for at least a decade longer than it should have, because Prabhakaran refused to surrender, even after everybody else quit he said that he would die first. Some reports said that he carried cyanide capsules with him in case the worst happened. If true, it is a mystery why he did not use them.
What really broke LTTE was the Christmas tsunami in 2004. It wiped out much of Sri Lanka's east coast, which was the bulk of Tiger ruled territory. After that, most of the guerrilla leaders quit, apparently interpreting the tsunami as God's wrath. From there, Prabhakaran and the Tigers were on the run, steadily losing territory. The Tamil apparently saw the tsunami as divine judgment as well, for most Tiger support vanished afterward.
So basically the Tamil lost their war because of what Americans would call an Act of God, ie an unforeseen event that changes the playing field and society. The Act of God is a longstanding legal principle in the US, saying that a contract can be broken if unforeseeable circumstances arise. The elimination of the American national passenger train service was junked due to 9-11, for example, although a Republican ruled Congress didn't want to but couldn't ignore Americans taking trains instead of flying out of fear.