So I thought I'd do some random analyzing of the upcoming development goals... Warning - I'm commiting the cardinal sin of estimating completion time. I've never managed to estimate correctly, so take them as die rolls at best.
Job Priorities
General: This can and should be a single release - there are no real reasons to break the four bullet points up. Maybe the mining options could get a seperate release if the other portions drag on too much or Toady comes up with a lot of them, but I kind of doubt that. I'd estimate that on the whole, Job Priorities will be finished on a weeks/months scale. As an upper limit, three months, likely less.
Tangents: Low change of tangents. Whatever mining options come out of the fourth bullet points could result in some tangenty stuff, but I doubt it.
Raw Changes: Practically zero chance of raw changes. Unless some really, really unexpected tangent happens, there shouldn't be any raw changes. I would expect some init changes, though.
Inns and Taverns
General: Presumably, there'll be several releases for this. The releases I see currently are Zoning/Jobs/Guests, Guest Interactions, Item Usage/Music/Dancing, Recipes, and Games, with most of them being flexible when they are done. Obviously Guest Interactions would need to be after Zoning - what I mean here is the extra interactions, like hiring mercenary guests, not the standard interactions like serving food and gaming with them.
Updating the Adventure mode taverns might be a separate release. Games might be folded into Item Usage, or that one might be split in other ways. Inns and Taverns would also be the point where Toady handles the multiracial fortress issue as per comments he made earlier. It's going to be a long road. If everything goes smoothly, this may take a year, but it's quite possible for it to go 18 months.
Tangents: There's a decent chance for small to largish tangents here, I wager. The smallest tangents would be tea and coffe, I think. Toy use could lead to some conflict work with mock fights with toy weapons. The new zone work could lead to some experimenting with replacing the kitchen workshop with kitchen zones, perhaps more. Roadside inns could lead to other roadside mini-sites (or however these inns are implemented) like shrines. Taste types might be this or an integral part of recipes
Raw Changes: It's basically impossible that there won't be raw changes here. There'll likely be new skills, which need to be linked up with instruments and such, instrument and toy raw could use some updating as a whole, games and recipes are likely to get raw files (the latter of which might hopefully get REACTION_CLASS renamed to MATERIAL_CLASS)... Toys could get some kind of toy use hint (single play, mock fight). There's a lot that could happen here.
Non-Player Artifacts
General: This'll be single release most likely, and quite a bit of the framework needed is already in place. This could go by quickly, depending on tangents and type and origin of artifacts. There's many avenues to generate artifacts - god-given gifts, demonic equipment, megabeast-hoarded/guarded/created item, regalia, a hero's or even god's signature item...
Tangents: Again, there's a decent chance that there'll be tangents. It's the perfect time to update kobold settlements. Thief lairs, non-historical creature lairs for beasts that steal artifacts. Historical Lairs that stay around if something interesting is in them. Toady mentioned the potential of magical artifact powers. Raw-defined artifacts that can get placed in the world in addition to the created ones.
Raw Changes: There's little chance for raw changes to happen, but there is a chance. There might be a creature token or three if megabeasts get to hoard, guard, or create artifacts (though curious beast megabeasts might just start with something in their hoard). There might be a few more possible changes, but unless there are raw-defined artifacts (unlikely), there won't be many major changes.
Fortress Starting Scenarios
General: "This is big. Really, really big. No, bigger than that. Even bigger. Keep going. More. No, more. Look, we're talking adamantine and slade spires for jewelry. This is big."
The framework that Toady outlines is a pretty big thing. Laws, customs, rights, status... This is a lot. This alone might see two or more releases. Hill and Deep dwarves probably want to come in after that with their fortress relations and all that. The scenarios themselves may take another two releases depending on the work involved with each kind of scenario, and reclaims might well be an extra release on that as well.
Tangents: It's likely that there'll be multiple tangents coming in through the framework itself, so naturally that they hardly even count as tangents. Randomized ethics and values. God personalities and relations and descriptions may come through. Guilds may be a necessity or a tangent. There are a lot of possible laws, customs, rights, and statuses, and they'll hardly be color. This may mean work on fortress justice, though likely not adventurer justice. The hill/deep dwarf work might see a decoupling of their sites from the CAVE_DETAILED token. The entity work may also result in some additions for adventurer start scenarios. Giving sites "start scenario" relations may mean some more site types, like mines and logging camps springing up.
Raw Changes: The work done for Fortress Starting Scenarios is in a weird place in that it could result in a lot of changes and additions, or on little to none. Status and rights could easily find their ways into the entity raws. We might be able to specify certain core laws and customs. Or it could all be generated based on ethics and values. Start scenarios, even as templates, are unlikely to come out to the raws.