Elden Ring DLC Boss prediction:

I think there is a very good chance we will face a reborn Malenia boss fight that will be even tougher.

I also predict a certain jar-wearing gentleman will resume his noble calling for a while.

Reasoning:

Looking at the pieces missing between the Elden Ring in Farum Azula and in present day, it is missing a segment that looks A LOT like Miquella's needle.

I think that Malenia and Miquella share a conjoined Great Rune in the shape of Miquella's Needle or MAY BE even BE Miquella's needle, and from the teaser art, it seems Miquella will have a part to play in the DLC. I can't see a scenario where we would come into contact with one without somehow involving the other, mainly based on their shared rune's shape.

So I predict we will get voice lines and lore from Miquella, fight Malenia again.