it couldn't work as planned right now... because if you have 5 alts with herbalism, it would kind of ruin the specialisation they're planning on introducting.
rep integration into the quests, dungeons and raids as "hourly" missions... in no way similar to SWTOR companion missions and profession skill training ... sigh.
so if they're going to wholesale implement the companion system, or at least "the good parts", may as well improve on the good aspects of the achievement bonuses from alts, the family integration via capped alts adding levelling bonuses and customisation bonuses, short missions you run to boost companion rep, etc.
i don't mind the pillage from SWTOR, it's some of the better aspects from the game.
what i don't know is the benefit to having 11 garrisons on an account, or 1 good one, and 10 sad panda's on the others.
what could work, is if
1. the garrison is a personal phased city. like sunsong ranch.
probably 5 phases, for variety/expansions. with spawned NPC's depending on the owner's. similar to half-hill's farm where you can add a mailbox, plow, sprinklers, etc. i get it.
2. leave pandaria.
it would have to replace sunsong ranch at some point so we can all GTFO pandaria. so it would probably need to have something to sell or collect, find, craft, discover, craft, buy and sell and collect and craft again, etc.
3. an account bound garrison,
so your level 11 could get a bonus to skinning, mining, herbalism, first aid, whatever, that came from the level 98 you have on the same account.
... +10 to epic bandage crafting bonuses ? etc.
4. each alt gets their own manager / butler / majordomo managed by each alt.
i.e. each alt can alter their companion armour/appearance/race/skillset.
so, if each alt has a majordomo in the guild who inherited your skillsets, a protege/apprentice that looked like your alt, it would add a collective bonus in a group setting.
whatever the garrison is supposed to do for individual characters, it will still do.
5. shared garrison XP, or, account-capped XP per week. i.e. a weekly token/quest to boost garrison resources.
functionally, the only worry i have is if they try to push the idea that a player can use 10 different garrisons with 10 alts. if they use that majordomo concept, they can link the garrison rep to a daily/weekly XP allocation & cap, like the guild levelling cap and the valor cap.
6. "boosting" a single peon/worker with many alts via rep farming = death.
either the garrison will accept that people will create alts to "farm rep" for garrison construction, or there will be people logging in every 2 hrs 14 minutes on alts to complete a quest/dungeon/raid for rep farming garrisons.
they can limit some of the reward systems to a daily cap so that alt-heavy accounts don't need to swap between alts every 47 minutes, or 2 hrs 13 minutes, or 12 hrs 11 minutes, etc. to rep farm between garrisons.
7. queueing up garrison tasks for your alts, so you don't have to log out and in on all your alts to check progression.
if players need to be online during that time, i can't expect that a lot of people will enjoy using the garrison system as intended, they will farm up to 1 garrison rep over 2 weeks to a month, then quit the game in frustration. e.g. pandaria dailies.
or, they can realise that people don't really enjoy waiting, and set a Primary Peon/NPC as the garrison VP/2nd in command, who gets their personal bonus when you're logged in, and multiple alts can use the same VP/2IC to boost the rep, or different VP/2IC's up to a capped amount per week.
8. integration into the remote app.
90% of what the garrison appears to do, could be done with a JSON/REST API and a website, i.e. a city RTS / tiny tower implementation.
adding in alts to the garrison, doesn't alter much to the database, it makes management easier to separate if they use something like the void storage or the pet/mount storage system to store garrison inventory, NPC characters and NPC rep/levels , resource and resource unlocks, names for buildings, building progression and building bonuses earned.
if it's stored as an achievement or quest progression, the remote client can even display the current garrison on the screen using a web graphic, and fill in the details in a table, offering quest/dungeon/raid mission progress and accepting/cancelling current missions from a web form.