I feel like, even if Krystal isn't on the main roster, we might have her as DLC. And then she could make the jump from DLC to in game content in the next iteration.
Really hoping we'll have her as a character. While I'm glad there's more females this time around, I would like it if there were more females that I actually liked...or females I would have nothing against. So far, Krystal hasn't been deconfirmed and it makes me hopeful for her inclusion given she was popular at the time of SSBB and that she's still supported. Not only on this website, but also some other places.
Then again, I say this but, um... She's on the same boat as Ridley, K. Rool and Dixie. Other characters that I would like as well. But since DLC is considered, and Krystal is arguably a character with a strong fanbase, I think she would be picked and developed after the game has released if she wasn't planned for this entry.