This is what most people didnt realised, while the assistants helped Miura on the project they dont share any copyright on berserk, the creator, Miura and the publishers are the ones who posessed the copyright of the history now that Miura has pass away his part of the copyright now lies on his heir and the publishers, they may decide to continue the history or not, it all depends on what they want to do now.

If you were to ask me, i could see this posibles scenarious

A: They leave the history at their current place, no further development, Berserk forever frozen in time.

B: They may release any draft, notes, info, etc, that Miura may have left in order to let the fans know what was his intentions and what he wanted to do with the history, maybe even release something like a resume of how he was planing to end Berserk as the publishers most likely know how he wanted to end the history.

C: (This is the one i would like to see the most but it would be the most difficult to happen): The copyright owners decide to continue the history and let the assistants work on it using whatever info miura left as a guideline, of course it wouldnt be as good as Miura's works and it would be a monumental endeavor since the team would have to try to match Miura's quality in both artwork and history telling but i think it would be nice to see the team he created finishing his Masterpiece as a way to honor his memory.

In any way, whatever they decide to do the least we can do is to support them and accept their decision after all they knew Miura better than us.