Why would the most successful team on the WC level pull out of TC? I don't see it happening anytime soon. While the 417 V5 is .1-.2 sec down on pace in the hands of the RC elite, it is still more than capable in the hands of mere mortals. I'm sure Tamiya is developing their next ride as we speak, and it will probably look a lot like the Raceberry setup with a Tamiya twist. To assume that the sky is falling because an almost 3 year old design needs an update is just silly.
As far as Tamiyas not showing up in the stock standings at big races, that is an easy answer. They do not sponsor any stock drivers. How many guys will make the A-main in stock at the ROAR Nats, Snowbirds, or IIC that don't have some kind of chassis sponsorship? My bet is none, and if that did happen I can guarantee that they would have one before the event was over.
The sky is not falling!