I don't think it's viable with the actual system we have now: making a new traderoute cost money and sometimes the same trade route, as we all unfortunately know, may disappear 3 or 4 times in a row, costing a pretty heafty of money for a small state.
As it is now, you get the popup only in the capital region, so you go, check why it disappeared, and if it was a rebellion or a big civil war, you'll avoid the same trade partner, or it's nemesis, until the region is stabilized, using another source of the trading good in the meanwhile.
The risk would be for governors to BURN an hella lots of money to make new unfavourable trade routes.
and Internal trade routes are highly strategic, so it would be preferable that only the player should be allowed to do them. Selling a trade good outside, will allows to gain a pretty heap of money in the long run, while internal trading give you very little.
For the purpouse of trade routes made by governors, in my suggestion in SPQR, they'll use their assigned "regional money", without touching the treasury, that's viable.
Also the devs could implement a screen, like the one we have now, were you can set which trade goods governors are allowed to use for "international trade" and which ones only for internal (that in my vision will ONLY be touched by the player's careful internal strategic trade routes setup)
You are probably right, I completely forgot about the cost. I played my last 2 games as antigonid and Egypt and that kind of money was never an issue so it slipped from my mind.
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