Ah, next episode is the finale. It looks sad. I wonder what happens... I never really loved YumeKira Dream, but I did when it had Himespetchi. It used to be okay until Coffretchi came along.
My guess is that in order for Yumemitchi and Kiraritchi to become idols, something must be done to the Yume Kira Bags... the magically get poofed into nothingness maybe...but this will cause Yumecantchi to disappear / DIE! So the Yume Kira duo must choose between being idols or Yumecantchi. They choose Yumecantchi, and they get transported into the dimension where Yumecantchi comes from forever.
Corny, I know, but that's my best guess.
Self-proclaimed biggest fan of Tamagotchi <3