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1. Maybe, but not from Ubisoft.
2. There was an idea to create something similar for Heroes 4, but in a slightly different style. Two add-ons were released for Heroes 4, but there was no game based on the Chronicles system.
3. If it is high quality and does not contradict the lore, then yes.
4. If the Chronicles are for the fourth Heroes, then learn more about the history of Axeoth (as long as it doesn't deviate from what is already known), if for the third - about the history of Enroth, Antagarich, Jadama, etc. You can have both.
5. Currently, there is a very good and promising project for the fifth Heroes - Legends of the Ancients, which is a continuation of the previous universe, set in the world of Heroes 4 - Axeoth. Perhaps this is what could be considered "new Chronicles." http://lota.celestialheavens.com/
Regarding the connection with Might and Magic: /topic/3323/
The last Chronicle does not end with the destruction of the world; there is still at least a couple of months of gameplay left.
Executor, before the Chronicles about Tarnum? After all, you don't like science fiction.