I think with "5-10 year old recognition" as a criterion, you've stepped away from reasonable reality checks. The fans they're worried about guessing are squarely in the 11+ age bracket. If they said glass, then yes, the non-crayon-using segment of Civ gamers would quickly guess Venice.Also, whilst to some glass might scream Venice ask yourself two questions:
1. Would a 5-10 year old get Venice immediately from Glass? If not, then it's not that obvious.
2. How would it be implemented? It's a manufactured good, not a specific resource, it would have to be a UA.
I suppose glass could be the output of a building as easily as anything. But the long and short of it is, I tend to think Italy has more interesting things it could doing than producing glass.
Ah, I see. You posit that not showing us Italian city-states could be part of a plan to fuel excitement about a civ that they're not actually going to give us. In other words...The only difference from the above is they are covering up the Italian City States as they want us to speculate, despite it not being included (as it would have been decided before this speculation began). They wouldn't hide the replacements.
Spoiler :
...they're evil.