At this point, it's utopian to believe that the EU will be able to continue as-is for another decade. A priori it also seems unlikely that the EU will reform or that the EU will collapse, but these are the three utopias/dystopias that are typically mentioned.
And I think "continue as-is" is the least likely of all. Such a development is not sustainable, neither for Germany nor for the South. In Germany, the negative interest rates are destroying the pension funds and, more importantly, the Sparkasse model - and 50 million out of 83 million Germans have their bank accounts at Sparkasse. Even if the big fish tend to use other banks (which are struggling as well but are freer to compensate by speculating on the stock market), the German state will not be able to make good on its promise to insure the deposits of 50 million Germans.
In the South, seasonally adjusted youth unemployment ranges between 25% (Portugal) and 43% (Greece). Even France has 23% youth unemployment. And this has been pretty much since 2010. The promise of improvement "just around the corner" won't be believable much longer - many already don't believe it and have punished each establishment party that promised it in turn, or that was tone-deaf to the reality that people are living. You may well get a crisis. And consider that the IMF planned to orchestrate a close brush with a Greek credit event in summer 2016 (as they did in 2015) in order to force the EU to find a solution. They couldn't do it then because their plans were leaked, but if they were ready to do it then, who says they won't do it on another occasion.
Now when we talk EU reform, many groups and indeed heads of government have plans that won't work because they'll require treaty change, i.e. the approval of 28 national parliaments through a process that may well take several years. That is why DiEM25 has come up with innovative ways to stabilise the situation that could be implemented tomorrow morning if a few key people agreed, without the need to change any treaties.
For example the introduction of an EU-wide food stamp program funded from TARGET2 surpluses. It's not necessary to turn the EU into a federation in order to have this kind of very basic federal program, which would let off the populists' steam in the hardest-hit countries (the ones that incidentally cannot currently fund an own foodstamp program).
Or having the ECB relay its ultralow interest rates for national debts amounting to up to 60% of GDP, while debts above that amount would continue to run at the rates each country can procure. It would immediately reduce Europe's debt burden by 1/3, while not creating moral hazard for countries to get any more indebted than necessary. In fact the incentive to stay within the Maastricht boundaries would be much higher by having a great differential between Maastricht-compliant and non-compliant debt, whereas right now the worst that can happen is having a fine slapped on you.
DiEM25 also foresees hypercharging the European Investment Fund and European Investment Bank, which have a mandate to prioritise helping structurally weak regions throughout Europe, and to prioritise forward-looking investments e.g. in clean energy, infrastructure and digitalisation. Poland currently generates 75% of its electricity from locally-mined coal. Those jobs are not going to be there in the long run, so if EIF investments and expertise helped them gradually build up a clean energy industry there, we could prevent an unemployment crisis at the same time as improving Europe's ecological footprint. All these kinds of things could be executive decisions with no need to push legislation through 28 national parliaments. Of course DiEM25 also has more ambitious plans - a European constitutional assembly is one of them, in order to create a less cartel-like and more democratic European governance model in the long run - but the sequencing is clear: first we need to stabilise the situation, afterwards there may be popular support for rebuilding the EU.
And the most beautiful thing is that this is the best course of action independent of whether we believe that the EU will continue to exist. We hope that it will, and that we will have a chance to let Europeans write a constitution for it, but even if it breaks apart, it will be better to do so in a climate of less poverty, less xenophobia and more international bonds between citizens.