Since it's confirmed now, let's speculate how far the story will goes on the next season.
For me, up to today, this is what have crossed my mind so far:
- Background of the characters will be revealed one by one, like their past, etc etc.
The one I hoped got their past revealed is Kotori, Honoka, Umi and Maki, but if I must choose, I think I'll choose Maki. Her background and past is so vague in the last season. - Maybe also involves how all the third-years (Niko, Nozomi, Eri) prepare for their colleges, and bit of their live at college.
- The Love Live! Tournament, of course. We miss this one on the first season.
- More about their "rivals": A-RISE, and maybe appearance of other idol groups.
- New members from the new first-year (which probably are Arisa and Yukino).
- The continuation of the school's condition: will it face closure again next year, or not.
- Oh one more, more new characters maybe? Too much new character is not good, though...
Well, that's all from what I'd thought so far. Anyone else want to give their own speculation?