Below are some possible scenarios:
* Zimbabwe’s economy and social system appear rapidly headed towards total breakdown, highlighted by a cholera outbreak that has killed over 560 people and by clashes earlier this week between Zimbabweans and angry soldiers.
* Street protests in Harare on Wednesday were another sign of the growing tensions in a country where nobody has money to buy food or meet other basic needs. Although the protests have been small and easily suppressed by police with batons, the weight of despair is clearly growing.
* Central bank efforts to print more money are only adding to stratospheric inflation. With exports collapsing, there is nothing to back the currency. Output of gold, which had been a third of exports, has tumbled as the crisis shuts mines.
* A worried army is taking measures to curb "rogue soldiers" after the disturbances. While there is no sign the army dissent amounts to a mutiny, the rank-and-file is suffering alongside other Zimbabweans and could potentially be a threat to the government as well as to public order.
* The confrontation between police and the rampaging soldiers earlier this week also raised the risk of trouble between forces once reputed for discipline and cohesion.
* There is no obvious breaking point, but the New Year has traditionally been a time of high expenditure for Zimbabweans. School fees and other costs fall due then for many. The government has lifted import duties on basic commodities to help make them more available for Christmas, state media said.
* The clock is certainly ticking on chances for the power-sharing deal.
* The spiralling crisis will increase pressure on both sides for agreement, although Tsvangirai’s opposition Movement for Democratic Change has said it will be another two weeks before it is even discussed again.
* Tsvangirai has been holding out for the home affairs ministry, which controls the police, but the most on offer has been joint control. The crisis could put greater pressure on him to avoid being seen as the obstacle, but there is no sign yet that either he or Mugabe will budge.
* If they do agree on a power-sharing cabinet, they could face a new struggle — reaching compromise on economic policy to ease daily hardships and persuade Western donors that reforms are in store so that they pump money into the country.
* Mugabe has said he will stick to policies such as seizing white-owned farms and plans to nationalise foreign-owned banks and mines — the last thing donors and investors want. Tsvangirai promises free-market policies.
* Western money would also depend on Tsvangirai having a clear say in the running of the country, quite apart from the fact that global financial turmoil means Zimbabwe is not a top issue and funds are in short supply.
* Control of security forces would also be a sensitive matter in any power-sharing government.
MUGABE TRIES TO GO IT ALONE
* Mugabe is waving a resolution from the southern African SADC bloc urging the immediate establishment of a unity government to demand the right to appoint a cabinet himself and has looked set to move in that direction.
* He could name a government alone while still keeping spaces for the opposition, but it is highly unlikely that main rival Morgan Tsvangirai would take up such posts. It would also be likely to simply prolong the stalemate with the same risks that entails.
* Mugabe could also face a hurdle in parliament, where Tsvangirai’s Movement for Democratic Change and a breakaway MDC wing now have more seats than Mugabe’s ZANU-PF.
* Western powers, including the United States and former colonial ruler Britain, would not accept such a government as legitimate and could increase sanctions. That could push the economy even closer total collapse.
* Impatience in the region is undoubtedly growing. The new administration in South Africa has been taking a more active role to try to press the two sides into a deal — symbolically putting some aid on hold.
* The spread of cholera to Zimbabwe’s neighbours, after the flood of millions of Zimbabweans seeking work, has given them another reason to want to ensure the crisis is resolved.
* But there still appears little will for more forceful intervention and the worsening crisis may lead, at least in the short term, to no more than an increase in the calls on the two sides to agree.