I am expecting Korra not to show any more interest in boys in the rest of the season though...
No reason she couldn't. Lots of people are attracted to both sexes to some degree. And Korra and Asami are about college age (21 and 22 respectively) now, which is an age at which a lot of people are experimenting and exploring their sexual options. There was a study a while back in which over 60 percent of female college students expressed at least some same-sex curiosity. (The percentage of male students who admitted such curiosity was considerably lower, but I suspect that's due to our society conditioning men to be more uncomfortable with same-sex affection and touch than women are, so the male students were less able to admit it to themselves or to a survey-taker.)
I had a friend in college who told me once (after admitting that she was attracted to the same unavailable female friend that I was) that she didn't believe in ruling someone out as a romantic prospect simply because of their sex. I think that's a nice attitude, and I'd like to think it applies to Korra and Asami. If Korra likes Asami, it's not about choosing women as a group over men as a group, it's about caring for Asami as an individual. It's more personal that way, more romantic.
Now, it certainly could be that the reason Korra and Mako didn't work out was because she actually liked girls better and needed time to discover that, but it doesn't have to be. The Avatar is about balance, after all, and she has been both male and female in her past lives, so I wouldn't be surprised if she -- or any other Avatar -- were bisexual.
Given that we are only a few episodes from the end of the show i highly doubt they'd start introducing a love story now for Korra.
Then again, since the show's ending anyway, and since it's already off TV, that gives them greater freedom to do what they want without worrying about the consequences. I doubt it'll happen, but I'd love it if the final scene of the final episode showed Korra and Asami kissing full on the lips.