Wierd... It's obvious that Kyosho doesn't have any problems because they are still releasing new vehicles. I wonder why Tower would drop them; especially if they were a profitable line, which I'm sure they were.
Why not just send Tower an email and ask them directly? Maybe there has been some kind of communication issue with Kyosho keeping them stocked with the parts needed or some other company to company issue. I am sure that they will not come right out and tell you the real issue, but they may release some sort of statement that we can desipher a resolve.