Keith, Left turning cagers are just like deers. Just when you think it is okay to roll on the throttle again, the cager will jump out in front of you. Not much one can do cept have a keen sense of awareness.
Always look for alternative/improvised routes. Say the cager will pull out, then is there room on the right? Anyone behind you? Can you break without being rear-ended? Every time is unique, yet every time is the same. Lot's of mind games.
Speed is most often the culprit in these types of collisions. Reaction time suffers. Thus, slowing down is the number one action. With the caveat of the cages behind you.
The only thing going for us is our narrow profile. That combined with (here we go) an aggressive riding style, is a risky yet workable alternative. Judgment of time and space are paramount. Knowing that you see the left pending turn, that the left cager is looking at the cage in front of you turning right, well then, you HAVE to assume the left cager will turn as the cage in front of you turns. Notice, there is no alt rt. The right escape rt is gone, the left soon will be. Hole shots and speed give us an advantage, and also get us in situations of no resort. Left turning cagers? Not much choice except adjusting our speed to take advantage of an escape rt or a full brake.
Riding is a game a chess. If you can't see several moves and their related consequences, well, never mind. The cage will find you.