My feeds were deprecated. Steps had to be taken. I first read the latest draft to inform myself again. I have read previous drafts multiple times to review them, but number eleven was not yet read by me.
Then I started updating my three Atom feeds. First the feed for the main weblog. Namespace change, remove the version attribute. I also updated the value of the xml:base attribute to prevent base URI trouble. (See also base URI examples.) I replaced atom:copyright with atom:rights, atom:tagline with atom:subtitle, atom:modified with atom:updated, atom:issued with atom:published and atom:url with atom:uri (unfortunate change, would have been much better to stay compatible with the WHATWG and CSS WG specifications). I also added a atom:link element with a rel attribute value of self, a atom:id element as direct child of the root element with a value of tag:annevankesteren.nl,2003:/weblog and that was about it.
I used to feed validator to test my new feeds and found a single bug. Apparently the validator considers ' to be a HTML like construct. This is of course impossible as ' is not a valid HTML 4 entity and it was merely part of the text only subject line.
Anyway, it was fairly trivial and you should do the same.