We have not received permission from Dygz to share the quoted post.
Guess I'm just projecting my own view of "guilded vs solo gameplay" onto his suggestion. I've already told him that there'll be general solo content like artisan stuff and maybe some solo mobs/questing, and, as you've pointed out, potentially caravans, but most of the top lvl content would be behind guilds.
In order to get great gear to be a great merc you'd probably need to be in a guild already. If by some chance you're are a pro at artisanal stuff and market gameplay, you might be able to buy some stuff, but I highly doubt that you'll be able to buy high lvl gear anywhere near the first several months of the game because guilds would be equipping their own people.
And even in a lot of artisan professions, I'd assume you'd need some support structure at higher lvls because you'll come across pvp competition or resource scarcity because some of the resources will be controlled by guilds (maybe not completely, but we'll have to see the design first to know for sure).
And if I was a top lvl guild, I wouldn't use a rando off the street in some important pvp event or a raid. And in order to become a trust-worthy merc, you'd either have to be in a merc guild that has built up its rep or you'd have to intermingle with a ton of guilds and their members, in order to build your own solo reputation. But at that point you're just "doing what the guild tells you" all the time, so I feel like that would kinda defeat the point of this thread.
The caravans would probably be the easiest way to earn good rep, but you'd most likely have to have friends to increase your chances of success. And we still don't know how Intrepid will prevent some exploits of that system, so there might be some problems for a solo player there too.