http://www.oni-tenkara.com/english/oni-blog/2373.html
I think you are misinterpreting his comments. I am pretty sure he is saying that when Gamakatsu introduces new rods, they do it only in the fall. I do not believe he is saying they are planning to introduce new rods this coming fall.
I think you are correct about the popularity of tenkara outside Japan driving future development. You noted previously that Tenryu once had a 270 length tenkara rod but for several years there had been no Japanese tenkara rods of that length.
In early 2012 I started importing the 9' Daiwa Soyokaze rods. Although they were not used as tenkara rods in Japan they were very poplar for tenkara fishing here (and used ones, when you can find one, sell for more than they did new). Although initially there was quite vocal push back from the competition, eventually, TenkaraUSA and TFO followed suit with short rods. This year, Daiwa introduced their NEO RT, which has a 270 length model. Nissin has only just announced additions to their Pro Spec tenkara rods, with the new rods being 270-315 zoom rods. I don't think a reintroduction of 9' tenkara rods is the first instance of Japanese manufacturers picking up on developments in the US (I think the first was Sunline bringing back a discontinued orange saltwater fishing line as a tenkara line following a couple years of it's use for tenkara in the US). I also don't think it will be the last.