Heller leaves it all open, they give themselves plenty of room to move
within the script. If they see something works they go with it. If it
doesn't they change. This then changes everything.

They are not
going to keep going with something if it doesn't work and right now this
Red John thing is keeping people guessing and it's working, so they
will keep screwing with us until their pockets are full of money and
then when they feel they have milked this Red John thing long enough
they will just create 2 episodes, get bits and pieces off all the worst
bits of who they wish, create an episode around that and bingo, there's
your Red John. Teresa could be Red John as far as we know, anyone could
be Red John. Just Teresa with her hand in a bandage could change
everything.  Get over it people. This is the reason no one can work out
this mystery. It's a scam!