Even my rather quick and un-thorough research was enough to reveal that not redingote but the swagger was the dominant coat style of the 1950's. For most of the time, both styles existed along side each other but it looks like swaggers were worn and certainly sewn a lot more. And if you include the swagger's shorter sibling, often called 'topper' it really reigns supreme.
However, I have tried to focus on the redingote.
In 1948, just one year after the introduction of the New Look, the redingote was very much 'en vogue' as this spread from Libelle shows. In the editorial comment, it is told that the skirts of the redingotes, like those of the dresses, are this year to be less full than the last (the real New Look redingotes) although coats should still be long. There are swaggers too, but the redingote clearly steals the show. I think this is the shape we usually have in mind when thinking of a "New Look" or "50's" coat. As you can see, a 1948 redingote could be either single or double breasted, might still sport shoulder pads (the double breasted one on the right page. In those days, that was considered a small shoulder pad and many were glad to get in back after the sloping shoulders of the New Look), had kimono- or set-in sleeves, a very tight waist and could have any kind of collar. How great and crazy is that one on the far right?
By 1951 things had changed. A lot. Swaggers and short wide coats were all the rage and the redingote, apperently, a thing of the past. In this quick search through my, rather limited (Beatrijs 1951), archive I couldn't unearth a single example of a 1951 redingote. Neither in the fashion reports...
... nor among the sewing patterns. And no, that trenchcoat-like one is not a redingote. It's described simple as a 'sporty coat' and from it's look I'd say it's completely straight and slightly pulled in with the belt. In fact, I've never seen the term 'redingote' used for a coat with a real belt.
For the winter of 1955 the same magazine, Beatrijs shows a very different picture. It's no longer all about wide coats but the old redingote hasn't quite returned either. This seems to be the era of the fantasy versions of the redingote. For the one above, the term redingote could maybe be used. It is gently fitted at the waist, has raglan sleeves and the skirt gets its width from loose pleast attached at the bodice some 5 cm below the waist.
On the next page, the second coat from the left has a more obviously classic shape but a decided kind of decoration with those huge pockets on the skirt. This page also introduces two new silhouettes: a business-like straight one of the far right and a loose-yet-shaped option on the far left.
In 1956, according to the magazine "Goed nieuws voor de vrouw" both swagger and redingote continue to be fashionable. If we concentrate on the redingote (look away from those marvelous suits on the right page!), several things attract the attention: The skirts are rather sleek, they have a lot less volume than that pocketed one from the year before. The collar is now the prominent feature. And then there's the closure, a probably rather impractical, long, single line of small buttons. This is, in fact, very much in line with the fashion for dresses at the time.
Finally, we get to the end of the decade, 1959, brought to you by Madeleine magazine. The heyday of the narrow waist is coming to an end. The fashion plates show wide coats, not so much the flared-from-the-shoulder swaggers of yesteryear but new shapes with clean lines. That's it from Paris, but from Italy, Madeleine can still report on a fantasy redingote. Once more, an option with a skirt gathered or loosely pleated from a below-waistlength bodice.
That's it for now. I think the use of the word 'redingote' may have ended with the 1950's or somewhere in the first half of the 1960's, at least in its use in the Dutch language. The coat it had come to describe didn't really disappear. It went in and out of favour, changed according to the requirements of fashion but in fact, it's still with us.