This would come down to the rarity of Ambassador consoles.
I estimate about 25-30% of 3DS consoles are Ambassador consoles. And the 3DS has been available for only a year. Imagine at the end of the 3DS's lifetime, a LOT more 3DS's will have been sold. Five years from now, there'd probably be under 5% of 3DS's will be Ambassador consoles.
That means only about 5% of 3DS's (if even that) will have the GBA games. There'll be no point with the NES games as they will all eventually be released soon, so the potential value will cut right in half.
But still considering that an ambassador console would have been purchased at the Launch price, those who've got the Ambassador games effectively paid that much for their 3DS, so the Ambassador games will account for the extra cash.
But remember what I said, the potential value will cut right in half. But only for the money that was effectively spent on the ambassador games will be cut.
As I'm in Australia and paid 350$ for mine, now it is 250$. So the worth of the Ambassador games for me would be 100$ for the 20. Cut that down to 10 games, and my 3DS becomes $50 more than the standard 3DS. So if my 3DS was brand-new, it would be priced at about 300$ But mine's still in a like-new condition, because I take care of it. So a little bit of the price should be taken off, let's say 20$.
Now let's go ahead to the year 2021, the 3DS is now 10 years old, and like all consoles after discontinuation (and after they're not being sold anymore), their price will raise slowly over time. I'd say with a 3DS that's worth about $280, it's price will have raised to say, 300$-350$ on auction sites. And add to that the rarity of the Ambassador system, the price will be raised slightly because of the increase of value.
But this is dragging on. To sum up, the longer you wait to sell an Ambassador 3DS, the more you'll get for it.
