Wikipedia is not a good example. It is freely licensed, available to download in its entirety and easily fits on a 30$ memory card.
In other cases those personal assistants could first ask permission to query an API or search engine.
In other cases those personal assistants could first ask permission to query an API or search engine.
That's a non-trivial modification, even before talking about the processor upgrades required to actually utilize that information and do local processing.
Your suggestion would drive the cost of an Echo from $30 to $300.