Last week's EU summit charted a roadmap towards fiscal union for its single currency bloc but did little to build a more robust firewall around friendless euro zone government bonds.
Senior European Union officials have said they fear a new crunch point early in 2012 once the financial markets return with a vengeance. Closer fiscal integration could well help ward off future crises but will probably come too late to solve this one.
Following are potential possible tipping points which could propel the euro zone into deep crisis:
Standard & Poor's has warned it could downgrade 15 euro zone members, including 'AAA'-rated Germany and France, if it judged the EU summit had failed to come up with meaningful measures to tackle the debt crisis.
The agency said it would reach a decision quickly.
A downgrade could automatically require some investment funds to sell bonds of affected states, making those countries' borrowing costs rise still further.
If France and others lose their top-notch credit rating, the euro zone's EFSF rescue fund which is underpinned by those nations will almost certainly suffer the same fate, placing further doubt over its ability to raise sufficient funds to ward off market attacks.
Rival agency Moody's Investors Service says it intends to review the ratings of all 27 members of the European Union in the first quarter of 2012 after EU leaders offered "few new measures" to resolve the crisis at their summit on Friday.
Fitch Ratings said the summit failed to provide a "comprehensive" solution to the crisis, thus increasing short-term pressure on euro zone sovereign ratings.
A ratings downgrade would further weaken the EFSF, the European Financial Stability Facility, which policymakers are aiming to leverage so its roughly 250 billion euros of capital could stretch further.
If the EFSF could be leveraged, with its permanent replacement the European Stability Mechanism (ESM), due to come on stream in mid-2012 with 500 billion euros of firepower and with plans afoot for the euro zone to lend up to 150 billion euros to the IMF to bolster its crisis-fighting abilities, there would be considerable resources available.
On top of the doubts about the EFSF, the ESM is still 6 or 7 months away and Germany has refused to let it have a banking license which would allow it to draw upon ECB funds while the United States and others appear reluctant to give the International Monetary Fund more resources.
As a result, the onus rests firmly on the European Central Bank's bond-buying program, and sources have told Reuters it does not intend to dramatically step that up. However, many analysts expect it to do just that eventually if the alternative is an existential crisis for the currency bloc.
Aside from the fear that investors will take a fresh, cold-eyed look at the euro zone as they go into 2012, the main source of concern about a crunch point early in the year is the profile of Italian borrowing needs.
Italy has 150 billion euros in debt falling due between February and April alone.
Analysts say Italian borrowing costs must fall significantly from around 7 percent before the spring otherwise Rome will need outside aid to avoid default. Some expect the ECB to be forced to act more decisively at that point.
There is no precise tipping point for Italian debt. The real danger is that the combination of high yields and daunting redemptions early next year will trigger a buyers' strike, meaning investors will desert Italy's auctions.
Italy, Spain and France together have to raise an average 17 billion euros of government debt every week in 2012, leaving plenty of scope for a funding accident.
Italy's technocrat prime minister, Mario Monti, is pushing through a harsh austerity program, including pension reform, tax hikes and spending cuts, which he says is vital to avoid Italy becoming insolvent.
Spain is under similar pressure. Incoming premier Mariano Rajoy has said he will announce new economic measures on December 30. He has promised to make tough amendments to a labor reform to help untie wages from inflation and to raise competitiveness partly through cutting business tax rates. He also wants to finish off a restructuring of the financial system.
PROGRESS TOWARDS FISCAL UNION
A pact among up to 26 European Union countries, after Britain opted out, to enforce stricter budget rules and win back confidence in the euro zone is due to be finalized by March.
A critical test will be how automatic it can make sanctions on those who break budget rules -- and making those sanctions stick.
There are doubts about whether the institutions of the EU -- including the European Commission and the European Court of Justice -- could be used to enforce sanctions without unanimous backing from all 27 EU states and about how binding the legal basis may be.
It may be possible to draft a treaty that finds a way around that obstacle but it may take time and Britain could raise objections if it wants.
All 17 euro zone members must also ratify the powers of the new ESM. The main hurdles to getting it up and running by July include getting the Finnish parliament to drop its detailed objections and persuading the markets that a cap of 500 billion euros is sufficient to handle problems in Italy and Spain.
GREEK BAILOUT TALKS
Under technocrat Prime Minister Lucas Papademos, talks about a second Greek bailout worth 130 billion euros are under way again. Athens wants to clinch a voluntary debt restructuring deal by end-January before the country heads to elections.
Banks represented by the Institute of International Finance agreed in October to write down the notional value of their Greek bond holdings by 50 percent in exchange for new paper, as part of the latest rescue plan for the country whose chaotic finances lay at the origin of the euro zone debt crisis.
If those talks fell apart, Greece could yet stumble into a disorderly default which could shatter any remaining confidence in the euro zone.
The EU has, however, now said that banks may not automatically take a hit in any future bailouts of a euro zone sovereign, saying the Greek situation is a one-off, easing investor fears that a precedent had been set.
The European Banking Authority said last week that Europe's banks must find 115 billion euros of extra capital to make them strong enough to withstand the euro zone debt crisis and restore investor confidence.
With interbank lending already all but frozen and banks parking record amounts with the ECB rather than lending to each other, the threat of a bank failure could prompt a new credit crunch which would take the crisis to a new level.
(Reporting by Luke Baker, Julien Toyer, Mike Dolan, Writing by Mike Peacock. Editing by Jeremy Gaunt.)