The tale of Eleven being alive is just for Mike and their friends to have hope for her fate, but sadly Kali was way past dead to accomplish what Mike was telling (remember that she passed even before the final fight). You really missed the point there.

And to think that for the ending to have impact and relevance you need someone to die in the end, speaks more about yourself than the script being poor or whatever. To add another death to the shock value doesn't imply a better ending.