The series has never stayed true to history. It takes a basis in fact and twists it to fit the story. Also, the Assassin attire never really looked discreet. Most Italians in the 15th century didn't wear thick, bright white hooded robes and carry a sword, dagger, crossbow, throwing knives and other weapons on them.
Most didn't wear those things, some (the Assassins) did.
The thing is that the attire that they wore in the series up to this point is understandable in some respects. It was the most fitting with Altair. From there it has been getting increasingly stylistic and blends in less and less. However the renaissance in Europe was a time of extravagant everything. Especially in the social circles the games put you in with Ezio. The hood kind of kills it imo but it was something that at a quick glance would blend in. At a closer look it was painfully obvious that Ezio or Altair were out of place. So in general that was a bad gimmick to me. But it at least had some basic credibility. Not much but some.
In colonial America the things that were worn do not match up well with what this new incarnation of Desmond's ancestor is wearing. There is no flamboyance for him to blend into in the Americas, or at least very little at that time. Most of the clothing worn in those times by most people were types of browns, dark blues, greens, blacks, greys or whites. Subdued colors. So he kind of has that much going for the outfit. However, few people wore hoods, it was suspicious, and no one wore a hood like the one in that concept art. That is the most our of place thing of the whole attire. Then add the various out of place decals and I really cannot see him walking down any street without about 90% of the people who see him doing a double take and instantly burning the image into their memory. Which is great for the police force or militia who will ask those people if they have you seen any odd looking people about, and guess who is the first person they will think of without a single doubt as to who the guard is asking about? Exactly.
Ezio was just another of many flamboyant renaissance men with a penchant for outlandish clothing styles. He also wore a sword which was common at the time. He might stand out a little but when there are hundreds of people like him he does not stand out as much. The games style simply does not lend itself well to this setting imo. You can look at all the variations of clothing worn by people in the Colonial Americas during that time and none of the common clothing will match up. Maybe a few of the exceedingly ridiculous fashion styles that reared their ugly heads at the time might show up but I doubt it. Even so, those always turned heads.