They're probably not a great investment, monetarily speaking, but for me, it's the thrill of the chase; collecting them with my kids. Opening packs and hunting down the cards we need is the fun part.
I think the e reader cards should be much more valuable at this point, but not many people are into those these days. Personally, I'd much rather have a complete e reader set of cards than amiibo cards. ;P
Looking back, I would have only collected the ones I like/love. That includes the figures. I don't have an issue spending on each set (I buy 20-25 per series) so much as it's a pain trading them. The traders are great, don't get me wrong, but it's very time consuming shipping off each trade.
And as far as what they do; right now it's very much not worth it. I only hope they'll use them for something cool in the next AC installment.
+- Rosewynn Island Coming 3/20/20! -+
I spent so much money buying packs of series 1 and managed to get about 90 of the 100 with many duplicates. I decided not to collect any from the next 3 series. Instead, I ordered all the currently available AC amiibo figures for less than what I spent on the cards. I think the figures are nicely done and will display well on my shelf. John
its fun to collect and all but its costly so not going for a complete collection. i only go for my favorite townies. i believe these amiibo cards/figurines will be useful in the new ac nx game. we have already achhd and acaf where amiibo cards/figurines are usable so i dont think nintendo will just end that. you can also take the zelda twilight princess hd and star fox zero just the two latest games. there have been released various zelda/star fox amiibo figurines before these games was released and they are supported in the game now. so i think thats enough proof, that we will get the ac amiibo cards/figurines support in the new ac nx game too...