Which also reminds me, didn't Kisame reveal that Tobi was a former Mizukage too?

Sort of. He was the shadow ruler during the time when the Three Tails, Yagura, was Mizukage. But that was only the most recent one before Mei, so it's within the past 20 years. Thus it doesn't give us much of a clue about who Tobi is. Also, Kisame thought Tobi was Madara.

Quote from switchgear

Tobi is not Obito backward. Even without the O it is Tibo. Though a anagram is possible, though a very poor one.

It would be rather funny to see the justification of the Ramen Guy.

Obito seems like the safest bet right now, but I kind of hope it is a new character connected to Obito, Rin and Kak ...

You're thinking in English. In Japanese, Tobi backwards is Bito, which is Obito without the O

ya, and the O may be because the same weird rule where they put o before the bar names 😛