I haven't made any decisions. There are lots of things that have come up in the past where scripting has been a natural extension/solution and I've been trying to find time recently to think about some of the options.
Even the most rudimentary standing production orders implementation is going to have to involve some kind of if-then structure and a way to get at certain game values/sums, and then it's a question of how that's going to work. My own scripting stuff (which exists for some of the diplomacy but is quite godawful) would be too clunky and would be reinventing the wheel. If a scripting language is used, it's a matter of whether it is available in the raws or if you'll just be able to enter some simple actions from a manager style screen, from which scripts are then built internally. I suppose there would be utilities written that grab onto that and stuff scripts into the system even if there aren't scripts in the raws, but it would be limited by the script-DF interface in any case, as far as I know. It would be a little strange to have universal management scripts that can do all sorts of things and be run any time, in part because of the accessibility issues, and because it's just sort of strange and unnatural to me to have a game that works that way, but that's exactly what a standing production order is.
There are future issues -- take creature special abilities or artifact magic. It seems like that's inevitably going to involve some kind of scripts, and at that point, there will have to be a measure of interface with the guts of the game. It's a lot of work to do that, as Footkerchief mentioned, however, it's a lot of work any way it is done, because the magic/abilities have to have effects/targets/etc. and that'll have to be kept up to date and access various parts of the game, pervasively if the typical variety is allowed. It's similar to an actual API for the graphics/etc., but I don't think it'd be nearly as difficult to maintain, since there would be a fraction of the options, and it doesn't raise any of the other concerns. In any case, I'd always wanted to have a game where you can do a variety of magic effects with a lot of freedom, but the more power you have, the more like programming it seems.
Random creature generation is another example. The forgotten beasts are hard-coded now, but I was considering starting with the random dragons out in the raws. This would involve scripting again. I don't know if this is at all similar, in terms of the concerns people are bringing up. It seems like it's a matter of how central something is to the game. The ability of some people to build water computers doesn't seem to bother most people, because that's sort of difficult and specialized, whereas presumably a script would be easier to use and would have more applications.