Except that, people continuously ignore ever increasing levels of automation and don't think its an actual threat and live under the false notion that 'somehow' new jobs are just going to materialize, even though the rate at which new economies grow is basically at an all times low.
Mind you, automation technology is DECADES old, and now its becoming that much more cheap enough for implementation on an even large scale (a lot of the production industry is already automated) - the rate of which its becoming cheaper (from a monetary point of view of course) is also accelerating.
In the next decade alone, molecular manufacturing along with extreme levels of automation are going to take over in large portions (even though we could implement it today).
Majority of manual labor will be completely replaced by automation - and once that happens, the economy will eventually crash (this will probably occur in the next 20 years, at most, though a huge crisis is probably going to hit in the next decade or so) because the rate at which machines will be replacing humans (in ALL fields) is inevitably going to be faster compared to the rate at which Humans can retrain (this is already happening).
Also, 'growth' of new jobs is not that likely in the face of technological automation. Why use humans if you can automate it in the first place? And don't kid yourself that we cannot do this. It will actually be easier to automate specific tasks that to spend time training Humans to do this (again, already happening).
The question remains is... what then?
Well, here's an idea.
In order to make the transition as smooth as possible (and you know... avoid devastation of massive proportions born out of ignorance), educating the global population with relevant general education would be paramount.
We already had the technology and resources for over 100 years to solve most of the problems we have on the planet - was never implemented due to notions of 'cost efficiency' and profits (and of course the preservation of the current socio-economic system which favors the minority in positions of power).
Full scale automation is going to eventually take over and no one is 'irreplaceable' in this regard.
Living in a 'garden of eden' might not be far fetched actually given that we had the ability to transform the entire planet with the technology at our disposal in 1974 to such a state in 10 years time (today, it can be done in less than a decade).
Whether or not we do it sooner rather than later comes out to how well the global population is educated on these matters.
Right now, things are changing because we live in the age of global communications where a decent level of the global population has access to relevant information.
The more relevant general information people are being exposed to, the less so will they be prone to being manipulated and used by those currently in power, and will be able to govern themselves in turn (which will eventually completely negate the need for governments and people in positions of power - though the political system is already in the stage where decision making is being delegated to machines at varying levels - this will only increase).
Once the crash happens, it will probably come down to the global population on where to take things next, or they will already live in such a highly automated world that they will basically have to do away with 'money' altogether because they will finally realize just how irrelevant it actually is.
And since the notion of 'working for a living' will already be outdated in the face of our technological reality (which has already been here for some time, it just takes longer to be implemented due to money), there's a good possibility it will encourage a different setting.
So... 40 years is a time-frame in which most of the global problems could be eliminated seeing the rate at which automation is being incorporated (although it could be done sooner - but educating the global population takes a bit of time) - and we certainly have the means to get rid of most of the worlds problems.
But it wouldn't be a 'perfection' or 'utopia' - just a lot better than what we have now (although, comparing that to what we have now may seem like a 'utopia' to many people seeing how most aren't even aware of what we can actually do).