I hope it's a girla and I think for the first name they'll go with something trendy and modern. For middle names they might use Renate (since Silvia is used for Estelle) or maybe Alice for Silvia's mum, and of course Marie for Sofia's. And it's time that Norrland gets more attention, so:
Olivia...
Well, I like it, and it fit in well with Leonore and Nicolas. And as they said, it's been a name existing in Sweden since at least the 16th century. :)
So happy about our new Princess. I'm thinking it might be a:
Elisa Renate Josephine, Duchess of Uppland
or
Mariette Renate Josephine, Duchess of Västerbotten
or
Esther Renate Maria, Duchess of Närke
or
Bianca Maria Renate, Duchess of Bohuslän