I thought about having a Animal Crossing themed graduation party next year, I was also going to buy my family a 3DS and a copy of AC: NL. I was wondering if Nintendo would shut down the online servers before then.
It's hard to say what they'll do. With more and more Switch games coming out, and with the Switch online becoming a paid subscription, there's a possibility they'd want to axe the 3DS/Wii U servers sooner rather than later. Why would someone want to pay to play Mario Kart 8 Deluxe online, when they could play MK8 on Wii U, or MK7 on 3DS, for free?
All we can really do is speculate. I assume your "graduation party next year" would be in the summer of 2019, which is a long time -- a lot of games and news will be announced between now and then, so there's no way of knowing for sure what'll happen.
Well, the DS and Wii online services being taken down wasn't a deliberate decision by Nintendo - the company Nintendo subcontracted to provide them went out of business. The 3DS and Wii U online services, and the Switch eShop, are managed in-house, so there's less risk involved there.
I mean, I guess we don't know for certain that they won't remove them in the near future, but you could say the same about lots of things, most of which will never happen (random example: an Animal Crossing MMO). And in the absence of any other evidence, it seems highly unlikely to me; there are still new first-party games being published for the 3DS, and even much older games like Pokémon X/Y, Monster Hunter 3 Ultimate and Mario Kart 7 still have a lot of online multiplayer going on.
There's no place like 192.168.0.0/16...
Time zone: ACC+5.
Yeah, all the family members I was going to buy for all live in the house with me. I guess you guys do have a point. I will see once it gets closer to June of next year, until then I guess it's money saving time