What makes you think that public opinion can be manipulated by the media/charismatic leader to _any_ position (left or right any anything in between)? While ideology is not determined by social/economic environment, there is an _elective affinity_ (as Max Weber would say) between the two. That is, there are certain ideologies that are more in line with political/economic interests of different groups than other ideologies, and those ideologies are more likely to be accepted by those groups with relatively little spin, while the other ones do not have much of a chance - no matter how much spin you put on them.
Imho, the conventional left ideologies (the mass-movement-mobilization-overthrowing-capitalist-oppression variety) clearly belong to the second category. They are passe because they do not have elective affinity to the economic interests of most people who make a living by selling their work today. They may resonate with the sentiments of certain segments of the third world populations - mainly because of their nationalistic, anti-US anti-North overtones which are skillfully manipulated and exploited by the local third-world elites to channel popular dissatisfaction with the status quo to external scape goats - but they do not offer the same vision of the future as the left concept of welfare state and public ownership of the means of production oferred to factory workers some hundred years ago.
Regardless of what we may think of free market ideology, it does have an elective affinity to the economic interest of most people who sell they labor for wages today. It offers them freedom of choice and freedom from institutional coercion, instant gratification of their needs and wants, expression of their individuality, and recognition of their individual skills and merits. These promisses may be illusory for most - but they speak to the economic interests of the working people today who do have considerable purchasing power. And more importantly, there is no alternative ideology that would have similar elective affinity to those economic interests. Preachinh the reduction of consumption and re-distribution of wealth is the modern version of medieval religiosity extolling the virtues of poverty and charity. It is crap nobody but a few fanatics will take seriously.
The left ideologies (such as marxism-leninism) became popular in the 20th century not because of their ideological appeal and calls for sacrifice, but because they offered a promise of better material life here on earth. Today, that promise, even if illusory, is being offered by free market capitalism. If the left wants to trump capitalism, it must come with a better promise of a good life on earth instead of pious calls for personal sacrifice for the cause.
Wojtek