It turns out that we aren't done with Mafia Wars Bangkok after all: the next content in game is now due to be Episodes 6 and 7 of Mafia Wars Bangkok!
You will have to finish Episodes 5A and 5B to participate in the 2 final episodes. As one blog reader pointed out, I suspect that these last two episodes in Bangkok will offer some higher-end animals to match our current equipment sets.
As far as release, I expect that this will come out in 2 weeks at the earliest but more likely in early June. I figure they will not release any content while Paris is still out, and it would be easy to let Paris ride into Memorial Day Weekend, have another holiday event, and then release Bangkok Episodes 6 and 7 shortly after.
Will have more info as it becomes available!