Is there any chance that Yugoloth's will appear in Golarian?
The 'loths aren't open content. However by way of the Tome of Horrors, some of them are open by way of their old 1e names such as derghodaemon (instead of dergholoth), etc.
What position they occupy and what roles they play in the heirarchy of Golarion's daemons remains to be seen. In any event, the charanodaemons/maernoloths are replaced by the thanodaemons as the servitors of Charon. The piscodaemon, derghodaemon, and hydrodaemon were never really major players within the yugoloth heirarchy and so it might be easier (and less derivative) to just go ahead and replace them entirely with daemons unique to Golarion's planes.
I don't have a specific soft spot for any of them (though I did write the dergholoth ecology last year or so), and it really remains up in limbo at the moment as to where I'm going to go with them. Whatever I do with them, it shall be cool however. I promise that.