http://www.stratege.ru/ps4/games/the_witcher_3_wild_hunt/article/50842
A interview in russian. Seems to be pretty deep, though the google translator sucks, so maybe someone who speaks russian can translate the most important parts
A part was translated by a english website:
"Yes, in the final version, you can not only use the boat to sail but also swim under water, opening up new areas that are inaccessible by land. We especially cut out the content for this presentation so you can focus all your attention on the combat system, monsters and ordinary people living on the mainland. But in fact,
we have designed five large islands and about the same number of smaller ones, which we have not yet demonstrated in public. So do not be afraid, in our game you will see a lot of interesting places to explore: ancient ruins, abandoned buildings, caves and much more. We created each of these places in a unique way for the players who want to get there. Some of them will be associated with Geralt’s story, while others just hide behind a lot of secrets. In general, they all carry some meaning. Our team spent a lot of time to recreate the world of Geralt and make it feel alive."
Asked about the role of the emperor:
"I still can not disclose all of the cards, but it will involve a number of interesting missions and yes, he will play a significant role in the plot. Geralt will have to work with him, but it absolutely does not mean that he has to obey his will, much less to agree to play by his rules."
"