It is true that Medieval II has extraordinary longevity as a game. :-) What we have not realized at the time when we actively developed the DotS was that we have pushed the game way too far and basically made it technically unplayable as the released Alpha manifests. These are the two main issues:
- Too many rivers on the campaign map making its rendering very buggy and crashing the map at places.
- Too many permanent stone forst (PSFs) processing in the campaign_script.txt. The script itself is over 70mb!
Both could probably be resolved by reducing the rivers and PSFs to more manageable numbers. IIRC there were some 2500 PSFs planned and my estimate would be that about 500 could be actually viable in a game.
However such change would compromise the research and careful plan for the campaign in DotS and would even mean that the map is way too big for it. Encompassing entire Sahara, Arabic peninsula and Iceland turned out to be too much. We planned PSFs to provide dynamics to all those regions but as it turned out the PSFs (or rather the scripts associated with them) were too much for the game to handle.
If I was to do it again today knowing the limits of the game I would argue for much smaller scope of both the map and the features we wanted to fit in. Probably even shorter time frame. Overall I believe it the DotS is a great testament of passion and dedication of hundreds of people who have been involved with it over the years but the ambition was much greater than what the game actually allows to do and for that reason it will not be revived or indeed "finished" since it is simply impossible.