Sorry, the current F-15J Fleet will last for another decade easily. As for the F-4's only a small number (40 I think?) need to be replaced at the moment. Which, can be done quickly and efficiently by just ordering more domestic built F-2's.
BTW Let's also not forget the sizable US Forces in Japan. From F-15's and F-16's to the USS George Washington and its Air Wing. (not to mention Air Forces in South Korea or Guam)
In short Japan has plently of time.
AND
I think you may be right. The media "noise" right now is of the tone, that the Japanese are not comfortable at the "pressure" being applied to get on the F35 horse ASAP. Japan holds all the cards here, it will be a multi-billion dollar contract. I am sure they will wait until they get an assurance of Japanese production (there is an important aviation industry in Japan - e.g. links to Boeing for Dreamliner), and technology transfer. Whatever plane they do acquire, will also I think, need to be tailored for their needs (which are different from most nations purchasing the F35).
This is getting somewhat away from the F-35 thread, but there are a few things which I felt need to be noted. There currently ~90 F-4EJ Phantom II's in JASDF service, with the most recent one manufactured in Japan in 1981... Given the age of the airframes, that fact that the aircraft is a 3rd Gen, as well as the increasing capabilities of other air forces and aircraft in the region, it does appear time for Japan to replace the aging F-4 EJ's. That is in fact what the
F-X programme is about, where Japan has been wanting the F-22, but also looking at the F-35, the Typhoon, Boeing's Super Hornet as well as the F-15FX Eagle, and even the Dassault Rafale.
The question which crops up, is just how long can Japan reasonably keep the F-4EJ's operational, and how long it would take the JASDF to achieve IOC and be able to start replacement with the various contenders for the F-X air defence fighter programme.
As for Japan being able to do local production of the F-35, and/or include local content, IMO any activity within the Japanese aerospace industry in concert with Boeing or other manufacturors is irrelevant. Given that the F-35 is a multi-national programme with tech tranfer, industrial participation and workshare involving a number of different nations, that introduces a host of additional issues.
At present, I am aware of only two assembly facilities, the primary one will be in the US, and a much smaller facility will be in Italy. It might, (emphasis MIGHT) be possible for the workshare partners to agree to allow Japan to setup their own domestic final assembly facility. I do not believe that the different workshare partners will agree to Japan engaging in manufacture of their own components without paying a premium to do so, since that would cut into a partner-nation's workshare. Additional, as I understand how the programme was structured (those who have more accurate or detailed info, please correct me) the various partners need agree to any changes, the US cannot just unilaterally allow Japan to being F-35 production. This I believe stems from the various partners all manufacturing components which will go into every F-35 of a given type.
An example of what I mean, is that if Australia's portion of the workshare is manufacturing the F-35A tail assemblies, then with the possible exception of the prototypes and some LRIP, all F-35A's in service would have an Australian-made tail assembly. If Japan decided that they wanted to have F-35A's with tail assemblies made in Japan, I believe that Australia, and/or all the other partner nations would need to agree prior to Japan beginning component manufacture.
-Cheers
hwell