While I have seen a bunch of books that use the new typesetting there was never once a book that shows dropcaps for me. Granted most books I tried are older and released before the new typesetting. And I suspect they got automatically converted without the input of the publisher. For example
Ghost Shadow and
Soul of the Desert have enhanced typesetting (kerning, ligatures, hyphenation), but no dropcaps. On these books I am sure that Amazon decided on their own to enable the typesetting - Maria (self-pub) neither opted in or out. Asked her about it and all settings when uploading were the defaults - not all her books enhanced either.
I think the automatic conversion is only temporary until a kfxgen is released for everybody's use.