The latest spasm of violent repression in Zimbabwe has sparked speculation that the era of Robert Mugabe may finally be drawing to a close. But the country's self-styled founding father and president since 1980 shows no sign of leaving voluntarily - and it remains unclear who or what can force him out.
Rather than loosening Mr Mugabe's grip on power, factional rivalries within the once monolithic ruling Zanu-PF party have enabled him, so far at least, to divide and neutralise his critics. Disaffection within the army and police over the impact of inflation on wages and prices - a national affliction - has encouraged absenteeism and desertion but as yet no overt mutiny.
The regime's willingness to use brute force, seen again in Sunday's beating and torture of the opposition leader Morgan Tsvangirai and others, has proven effective until now in discouraging large-scale political protests. The flight into exile of up to three million Zimbabweans - almost a quarter of the population - has necessarily weakened opposition on the ground.
Additional factors are contributing to Mr Mugabe's presidential longevity. The regime has systematically, although not wholly successfully, intimidated the judiciary while media controls and censorship mean egregious official incompetence and corruption often go unreported.
Most importantly of all, perhaps, the international community's ineffective, sporadic engagement has also enabled Mr Mugabe to thumb his nose at foreign critics. After Peter Hain, then a foreign office minister, reduced Anglo-Zimbabwean relations to a furious shouting match, Britain - the former colonial power - backed away from further confrontation and has largely looked the other way in recent years.
"I utterly condemn the violent and unwarranted action taken [against] a peaceful, legitimate gathering of Zimbabweans," said Lord Triesman, the current Africa minister, after Sunday's violence. "The United Kingdom holds Robert Mugabe and his government responsible for the safety of all those detained."
The question of what Britain would actually do if its warning were ignored, as it plainly has been, was left hanging in the air - because London has no answer.
The EU and the Commonwealth have also shown themselves powerless to promote change using limited sanctions and official ostracism. So too - for mistaken reasons of regional and racial solidarity as well as sheer inertia - have South Africa, Zimbabwe's influential neighbour, and the Southern African Development Community.
And while Bush administration officials occasionally talk about Zimbabwe as a rogue state and a threat to international peace and security, there is no thought of active, Middle East-style intervention there. The 82nd Airborne Division is in any case otherwise engaged.
Mr Mugabe, meanwhile, fresh from celebrating his 83rd birthday last month when he was hailed by state-controlled media as "an unparalleled visionary" and "an international hero among the oppressed", is manoeuvring to extend his time in office to 2010 or even 2014.
Mocking potential Zanu-PF successors such as vice-president Joyce Mujuru and former minister Emmerson Mnangagwa, he declared: "There are no vacancies. The door is closed." His birthday party cost an estimated 300m Zimbabwean dollars (about $65,000) in a country where most people do not have enough to eat.
"The party is so divided, it's difficult to see who could remove the old man," said Richard Dowden, director of the Royal African Society. "I don't think things have changed so dramatically that you can talk about the government being toppled. Mugabe is a master manipulator and he's still on top of things. He reads the situation pretty well. He doesn't look like a man who is about to give up."
All the same, Mr Mugabe's position is far from secure. The weekend's shocking violence may galvanise rather than deter the protesters, accelerating the consolidation of a united opposition under the Save Zimbabwe Campaign umbrella. Zimbabwe's prolonged economic and institutional decline may also be finally approaching a tipping point, rendering the country ungovernable.
And if the regime's brutality increases as it struggles to keep hold, the neighbours - and the west - may finally be embarrassed into decisive action.
Yet even if Mr Mugabe goes, radical political and economic reform, including a power-sharing transitional government and a new constitution, will still be urgently required, an International Crisis Group report concluded this month. "A deal that merely removed Mugabe while in effect maintaining the political status quo by keeping Zanu-PF in power would be no change at all."
Simon Tisdall