I'm confused. I got that email in my gmail account too. Does that mean they're adding USB Audio support by patching Android 4.4.x/4.5.x or do they consider the new Android L (aka Android 5.x) as the patch? For some of the older phones like my Galaxy S3 I don't have any hopes of Samsung releasing Android L for it. I considerate it fortunate that I even got 4.4.2 since none of the HTC, LG, Sony, Motorola phones released around the same time (early/mid 2012) even got 4.4.
I do think it will be only for the new Android release, but I hope I am mistaken.