Teh yuki became the machine god due to 3000000 repetitions of the Endless Eight summer, and eventually proved capable of being the human god's equal by forcibly disappearing Haruhi.
Mikuru (Big) still held unexplained secrets, but she was still just a normal person. Albeit a time-traveling one. If the series had continued to be written maybe at some point Mikuru would've done something besides be a sexy bitch with such big titties you wanna get molested doncha?