Ehhh... yeah, it's kinda hard not to see it that way. To be honest, I always found the whole "Korrasami" (which I'll put in quotes because it's not an actual word) obsession kinda creepy, but it was a rather sweet touch at the end.
On the whole, the finale was perfectly good. Still felt more like an extended ending of a season rather than a whole series, but whadyagonnado when Nick has been fucking the series up teh butt since day 1. I was rather let down by Varrick and Ju Lee (or however you write that) entering a romantic relationship, since I always felt theirs was the most unique, and I'd rather had it stay that way. It wasn't even that much of a stretch to assume Varrick was gay, or just devoid of romantic interests altogether. The giant mecha thing... meh. Would have probably been better if it didn't move like a video game character from the 90's.
Overall, I'd rate the series as a whole probably a 6.5/10, but I can't really blame it all on the creative team. It was doomed from the start, being the sequel to TLA, and Nick's batshit policies certainly didn't help. Season 2 was the pits, but season 3 still rules supreme. It was a bumpy ride, but certainly worth it, just for even a spark of that Avatar magic again.
You know what would totally make my day? A mini-sequel series where Korra and Asami just chill out on their vacation and ruin this whole relationship thing for everyone. Or fuck it, just make a whole series where the characters just do the craziest, stupidest fanservice things. Get Toph, Zuko and Katara reunited at an old folks' home and have them whine about them kids these days. Make an episode where Mako finally realizes broody cop isn't what he wants to be, and tries out a whole bunch of wacky jobs. Make Bolin a lavabending teacher. Or have him return to his movie career. Make an episode with Toph, Lin and the twins from season 2 where they just stand in a room and try to out-grump each other.
I'm not sure if there's anywhere for this franchise to go after this point. I'm perfectly fine if this is the last we'll see of Avatar.