I don't think that McAllister was Red John.

Not only would that be a terrible semi-ending and leave viewers hopeless of the next half of the season, but would also savagely dilute the whole purpose and meaning behind the series.
The preview of the next episode, My Blue Heaven, seems relatively similar to the time when Jane was with Lorelei Martins; he's in spirit, happy, but this isn't right.

Although this episode did disappoint everyone, I believe that the real Red John episode will be the last episode (or second to last). The writer has developed such a complicated and intense series and won't be ruining it by killing the whole point of the show halfway through the show's final season.

I don't think that the murder of the gym spy from a few episodes ago was Red John himself. It did lead to the discovery of the Blake Association which was progress, but the tattoo on Partridge's arm indicates another level of the pyramid; a sort of hierarchy. I don't think that Partridge was Red John, but merely a closer pawn than what Bertram was (three dots on arm).

My Assumptions:

There are many paths from here, but I think that the first three are in the next episode. With all possibilities, we are given the insight that Jane has found a lover and has moved to the California Coast Line (My Guess is Santa Cruz) due to episode 9's trailer in which Jane is seen walking the beach with a Red haired woman.

Possibility # 1 would be that Jane finds out that the woman is just another spawn of Red John, in which the season would immediately spark again and all of us viewers would be greatly pleased due to the restoration in the show's purpose. I don't think that the character of Red John would care if Jane were to kill him, the closest thing I can think of as far as resistance would be the death of them both (which would be the last episode logically).

Possibility # 2 would be that the next half of the season would be concentrated on assisting Jane's CBI team from the fury of the Civil Court. This would be a fan's nightmare and would probably end up being a Dexter-style ending to what was an amazing show.

Possibility # 3 comes straight from the trailer in which Jane is proposed re-entrance into the CBI and relief from the past charges that were placed on him. This seems to me like the most viable option and will lead to Possibility # 1. Red John enjoyed playing games with Jane from the beginning, it's the whole idea of the series. If Jane doesn't solve murders, Red John is left hopeless and bored (which was mentioned in an episode in a previous season). 

I'm not sure, all three are quite a stretch but I definitely think that the writer has a bigger plan for the series, one that would not disappoint fans. Agree with me? Click plausible! Don't? That's fine too.