Sorry -- I have mostly been working on Native, and I never did get around to posting that list of changes that I said that I would do. After that, I was probably going to work for a bit on the Northumbria mod, and then get back to Sicily. I'll try to explain why below.
By now, the changes in 0.903 are such that simply updating Sicily would require a lot of work -- essentially re-writing the mod from scratch. It's not just the new scripts -- also, the changes that make battles go quicker, such as the low-density models, would require a fair amount of work as well.
After visiting Sicily, I decided that I wanted a mod that flowed much more like the actual historical campaigns. This would mean the occasional appearance of very large armies, longer and more difficult sieges, and more realistic treatment of supply difficulties. I also wanted to include the changes in the seasons, as weather and (even more importantly) the agricultural calendar had a tremendous impact on when armies could take the field.
The downside is that you had long periods of time when nothing might be happening. The idea that I wanted to try and implement stems from a new operation that came up a few editions ago: set_player_troop. This opens up a whole world of potential. Bored sitting in a rain-swept siege camp outside Syracuse, or recovering from a festering arrow wound? Put your character on hold, and jump across to the other side of the island and become a merchant running caravans, a Palermo street thug fighting for control of the harbor offloading, or a peasant planning out how he is going to get through the winter. This also solves the perma-death issue. Slain in battle, but don't want to stop the game? Just take over another member of your party.
The problem with starting this out in Sicily, is that Sicily is was a very, very complicated campaign. In fact, that's why I chose it. To do Sicily right, purely from the top-down aristocratic perspective, you need to model dynastic politics (for the Normans) and inter-clan infighting (for the Arabs/Berbers). Also, you need to have both short- and long-distance trade in both necessities and luxury items, and naval warfare -- the sieges of Palermo and Syracuse, and the off-map siege of Byzantine Bari, all required major naval battles near the harbor that cut off supply and demoralized the defenders. To add in other social classes (aka character classes), you'd need to be able to reflect urban society in what were then some of the largest and most ethnically-diverse cities in the Mediterranean.
Northumbria seems to have been a substantially simpler conflict. The cities are much smaller and there is no meaningful naval element. Long-distance trade seems to have mostly been confined to wool exports. Also, many the dramatic events happened over a single bitter winter, which would mean that I could slow down the pace of the game and still include a lot of action.
MorgTzu had originally proposed Northumbria as a quick-and-dirty mod. I'm all for that, but I'd also like to take it and work on a somewhat different version, tentatively entitled "The Harrowing," in which the goal is both to survive the fighting and the bitter winter that accompanies the Norman attack. It is intended to be something like the game "UnReal World," in that managing your foodstocks will be extremely important. I also want the game to try to "track" a few dozen NPCs, ranging from Norman lords to ordinary foot-soldiers to peasants, to model their decision-making and record the major events. The player can meet them, fight them, interact with them, recruit them, or -- if killed -- switch to playing them.
This may sound fairly ambitious, but the new M&B now contains vassalage, raiding, sieges, and a bunch of other features that I won't need to try to implement from scratch. Also, M&B has a number of new features that make bug-fixing much easier. So, I'm hoping that I can work out a basic version of The Harrowing a few months after M&B Native is finished, and then use it for the basis of a more complicated Sicily mod. Essentially, I'll be building on previous work, rather than re-making a new system from scratch.
All this is fairly tentative, though, and I also need to finish some stuff for Native before taking on new projects.
Btw, if anyone wants to simply adapt the Sicilian setting to 0.903 -- ie, use the new raiding and siege system rather than the old -- they're more than welcome to do so, and I'd be very happy to help.