The Tigers' de facto state in the north of the island has been crumbling rapidly. They lost their political capital Kilinochchi earlier this month to a military offensive that has been going on for nearly two years.
But bigger battles may still lie ahead as security forces move to capture the coastal town of Mullaittivu, the last urban stronghold of the beleaguered Liberation Tigers of Tamil Eelam (LTTE).
Sri Lanka's defence ministry said the "countdown to extinction of the Tigers" had begun with the capture of Kilinochchi, where the rebels had all the trappings of a de facto state including a civil administration with a bank, courts and a police force.
Military observers agree that the guerrillas' chances of holding out are slim.
The rebels admitted 2,000 of their fighters were killed in 2008, the biggest single loss in a year, while the military appeared to have suffered fewer casualties thanks to the use of heavy weapons and air cover.
"They (the Tigers) are outnumbered," said Nanda Godage, a military analyst contributing to local newspapers. "They have never faced such a large force against them and it looks like their days are numbered."
Military officials say eight divisions are closing in on the jungle and lagoon district of Mullaittivu, where the Tigers are known to have key military bases as well as hiding places for Tiger supremo Velupillai Prabhakaran.
But Godage said: "I don't think the battle will be over after the fall of Mullaittivu," adding that a bigger challenge will be establishing a political plan to address the long-standing grievances of minority ethnic Tamils.
"If not, terrorism will continue," he added.
Former Tamil rebel-turned-politician Dharmalingam Sithadthan said the 37-year war had entered its final phase with the Tigers' backs to the wall, but political power-sharing was needed to seal the military victory.
"What we are seeing is the beginning of the end of the Tigers and this is an opportunity for the government to reach out to the Tamil moderates and ensure a devolution plan," Sithadthan said.
Tiger rebels have been leading a campaign for a separate homeland since 1972, but moderates do not want outright independence. They have been pressing for greater autonomy for the 12.5-per cent Tamil minority within a united Sri Lanka, where the Sinhalese are in the majority.
The Tigers have been accused of killing a large number of Tamil leaders in a bid to lead the Tamil struggle, starting with the gunning down of the moderate mayor of Jaffna, Alfred Duraiappah, in 1975.
From a ragtag bunch of fighters in the early 1970s, the Tigers grew to become one of the world's deadliest guerrilla outfits, known for their use of suicide bombers. They have also developed a sea-going capability as well as a mini air force, a rarity for any guerrilla group in the world.
However, Tamil commentator D. B. S Jeyaraj noted in the Daily Mirror that, for all their successes, the Tigers do not appear capable of resisting the current military onslaught.
"If the recent track record of the LTTE resistance is anything to go by, it does seem inevitable that the remaining positions held by the Tigers would also be overrun in the near future," Jeyaraj said.
Sri Lanka's military is not writing off the Tigers, at least not yet.
Army chief Lieutenant General Sarath Fonseka said they may still have up to 1,900 fighters.
But he said: "It won't take a year to finish them off," after President Mahinda Rajapakse announced the capture of Kilinochchi earlier this month, sparking street celebrations.
The Tiger rebels have not commented on the military gains. Tiger supremo Prabhakaran in November announced that they would fight on and regain lost territory. However, since then the Tigers have lost more ground.
The pro-rebel Tamilnet.com website last week said Tamils living abroad had "anxiously" asked about the future of the Tamil separatist struggle and the website had invited their suggestions.
"In this regard, TamilNet invites positive written opinion from its readers," the website said. "TamilNet also considers this as a healthy democratic exercise in inspiring the future course of the struggle."