Here is a recap of the U.S. Christmas issues. Click on the issue name to visit the specific page with details of that issue:
Holiday Window Views
Florentine Madonna & Child
Nativity 
Other holiday-season issues:
virtualstampclub.com
News and information about stamp collecting
I’m really surprised there is no Christmas Global stamp this year.
My best guess (and that of an expert I consulted) is that the USPS feels it has adequate supplies of last year’s stamp, or even the Moon Global Forever, which, after all, are supposed to be good “forever.” It’s also possible that the previous editions didn’t sell well enough to warrant a new one.
I can ask the USPS, but I don’t guarantee an answer.
In past years the global forever wreath stamps have stayed on sale on the online shop at USPS. Of course, there isn’t always a lot of logic to what USPS does, so you may be correct.