Nah you don't get it, winning isn't about surviving the battle.
For The Red Lotus to succeed they would have to accomplish their goal, and they could have done that even in death. Whoever is holding the pen for made the season end the way they wanted it to, and as a result they missed out on telling genuinely amazing story.
Then mission still accomplished?
From what we've seen after the fight, Korra might not even be able to bend. She can't stand, she can hardly make facial expressions.
She is broken, now I don't know how long that will last, but considering she hasn't Avatar State'd herself back to normal nor Katara hasn't swung buy to heal Korra up, we can assume it's pretty serious.
The poison was Mercury, Quicksilver. You shouldn't ever be in physical contact with it, let alone let it sit in your system, then get all fucking heated up, just making the toxins work faster.
Also Asami going after Korra would be baller as shit.
Not because of 'oooohh lesbians' but because of the setup being there.
Asami and Korra have both had a crappy relationship with a guy, got suuuper close, they were more chummy than anyone else in either of the shows in Season 3, then Asami presumably takes care of Korra for 2 weeks straight, maybe more and bam, Asami grows romantic feelings.
Seems plausible.