I sincerely hope that in the upcoming installment for the series, some combat stages are surprising and unexpected, like the Eternal Battle from Witcher 2. The stages should also be challenging enough that they require the player to be inventive and varied in their fight strategy- no simple solutions like drink these potions and you'll be okay.
Also feel free to add in additional bosses or fights exclusive to Hard or Dark Mode settings. This way anyone who wants to skip a hard boss, like the Kayran, is free to do so. Please take into consideration that success in combat is not hampered by PC performance issues, like failing in combat because the QTEs do not register during fights.
At the same time, it would be nice to have some sort of entropic element during combat like the QTEs, but one which is non-scripted and unpredictable. Perhaps make some enemy attacks unpredictable, so they rely solely on player reflexes to be countered.
Additionally, it would be nice to carry over development from the witcher training path, at least. Geralt has come such a long way, and it would feel strange to have him start at point zero if the player uses Witcher 2 file saves.
That's it. Thank you for reading, and thanks for all the awesome work you've done.