Not only did François Bayrou lose his seat, but the center parties generally succumbed to the logic of a presidential system and its strong tendency to become biplar. But perhaps Hollande deserves more credit for this than he's generally given. His "centrist" approach to his candidacy, along with Socialist dominance of government at the local and regional levels, has weakened centrist fears of the Left. Just as the line between extreme-right and right has become increasingly blurred, so, too, has the line between center and center-left.
There may be a sociological basis to this result as well. The Socialist Party is no longer a workers' party. Most of the "workers" it retains are in fact public sector employees: schoolteachers, government workers, etc. Socially liberal professionals are plentiful in both Socialist and centrist ranks. Many of these people do not share the anti-EU, anti-globalization sentiments of either the extreme right or the extreme light, and they are put off not only by the droitisation of the center right but also by its crass pursuit of wealth (the bling-bling factor) to the exclusion of other cultural values.
Throughout the campaign, and indeed throughout the past five years, I argued that the 2012 election would be won in the center. My confidence in that interpretation wavered after the presidential, because 1) Sarkozy made a stronger showing than he should have if the center had really deserted him, and 2) I think Hollande won because the extreme right came to detest Sarkozysme as much as it has always detested the Left. But the legislative election makes me wonder if, indeed, France may have become a country where the majority is now in the broad center, which stretches from, roughly speaking, Hamon to Bayrou.
Interestingly, this very diverse "broad centrist" electorate may be easier to please when the issues are rather fragmented, as they are in a legislative election, than in a presidential election where a few high-cleavage issues tend to dominate the discussion, and where personal characteristics of the candidates ("the incarnation factor") loom large.
So perhaps I was right all along to think that France is now a country in which the center is trying hard to hold, and succeeding, even if the self-proclaimed "centrist" party(ies) fared quite poorly.