As you may be well aware, France has had a notable number of riots, uprisings and revolutions in the last 250 years or so. I believe it the Fifth-Republic has been in existence for approximately 50 years, which is getting on to be one of the longer republics France has had. My question is, did the uprisings of May 1968 in Paris over student tuition fees mark the end of a trend of uprisings? Why has there been no revolutionary reactions to national or international crises in the last 50 years. I am aware that there have been major riots since then, but why no revolutions over the GFC, European Union etc?
Did the uprisings of May 1968 in Paris over student tuition fees mark the end of a trend of uprisings?
No, absolutely not. Then end of a trend of uprisings was la Commune de Paris, or perhaps even the French revolution of 1848. With the latter stopped the tendency for Paris and its population to topple the government of France (by and large, what is known as French Revolutions were revolutions of the Paris region, with the rest of France usually indifferent or actively opposed) while the former is the last large scale uprising against the Government (but it is unclear it would have taken place absent the humiliating defeat in the Franco-Prussian war). So they were no trend of uprisings to be ended almost a century later.
Note in particular that there were absolutely no violent uprisings of any significant scale in metropolitan France during the 70 years of the Third Republic (though this might in great part have been due to social changes having been triggered by the World Wars: many revolutionary new political and social changes were enacted during the World Wars or in their immediate aftermaths).
Besides, Mai 68 is much more aptly described as one the largest and most remarkable convulsions that accompanied the profound social changes which took place in between 1950 and 1980 in most advanced democracies than as a violent uprising against the then current Government. In other words, it is much better understood as a symptom of the baby-boom, the explosion of enrollment in higher education and the general change of attitudes towards sexuality and authority than as a political riot per se.
Why has there been no revolutionary reactions to national or international crises in the last 50 years. I am aware that there have been major riots since then, but why no revolutions over the GFC, European Union etc?
Probably because independent, prosperous, aging democracies very rarely descend into revolutions. If you want a more specific answer, the relative decline of the political, military and plain demographical power of Paris (and its region) compared to the rest of France certainly played a role, as well as the aging of the French population in the last 5 decades.
What was the legacy of Mai 68?
This is the question implicit in the title, though it is absent in the body of the text. Well, as Lennart Regebro's answer correctly notes, the political legacy was rather unimpressive in the short term. Interestingly, the two most powerful political parties of the time, the Gaullists and Communists, knew severe drawbacks in the the ensuing decade (the latter ultimately disappearing completely as a significant political force, and the former moving from its incredibly dominant position to second place within the French political right). At the level of social change, Mai 68 was part of a movement that changed deeply French social norms. This movement included the lowering of the voting age, the legalization of abortion and contraceptives and generally a much freer vision of sexuality, the generalization of higher education and of employment for both men and women etc. It is unclear to what extent the events themselves played a role, but certainly many concessions were made with a definite fear of students rebellions degenerating in general strike again. From a purely positional point of view, the cohort born in 1948-1952 (so the typical high school graduate or young student in 1968) did very well indeed in economic and political terms through the span of their life (see for instance Le Destin des Générations) and arguably still represent the dominant social force in contemporary France.
The May 1968 protests was in no way a revolution. It started as a student protest against various issues at the University of Sorbonne, and escalated when first the university leadership and after the conflict grew, the government, tried to solve the issue by calling in police. After this many other unions in France went on strike in sympathy. So it was not a revolution, it was a protest that involved violent clashes with the police. These have by no means subsided in France, but remain regular occurrences.
The immediate result was the the French national assembly was dissolved, and new elections announced. As this was done, the violence stopped and the strikes ended and people returned to work, so it looked like a victory.
In the elections the Gaullists won with a landslide. So on a short term view the result was in fact the direct opposite of what the students and unions wanted, as it resulted in the increased strength of the French right.
The 1968 events may be one of the things that has contributed to the partisan situation of French politics, although the main thing to blame there is the first-past-the-post system. But May 1968 has become a myth, a thing that you are either for or against, further cementing the split into a left and a right with no middle. This has lead to the virtual non-existence of liberalism (in the European sense of "liberal" as somebody who likes liberty) so in French politics there are no essentially just conservatives and socialists.
The long term effect of 1968 is that it has contributed to a political stalemate, where the right often wins the elections by promising toe fix the long standing problems in French economy, but then encounter violent protest when they try to fix the problems, and therefore give up. Sometimes the socialists win, but they usually don't do anything to fix the economic problems (I haven't kept up with French politics since I moved three years ago, so I don't know if the current socialist government is different).
The end result of that political stalemate is weak French economy, high unemployment and poverty.
It's impossible to say how much May 1968 contributed to this state. It may very well be almost nothing, but the significance many political writers assign to 1968 is hard to ignore. It may be that the impact of 1968 is mostly a myth, perpetuated in large by those leftist politicians that was involved. But it could also be that it has greatly contributed to the French political climate.