I'm not sure what the NPB has to gain aside from eliminating some MLB teams from putting a large bid in simply to block other teams and then not following through with a contract.
Also, while Japanese players are under contract for 9 years unless posted, they do not have to sign with a Japanese club to begin with. It could be a preemptive move by the Japanese Leagues in case they fear the youngsters would start to come directly to the US. By modifying the posting system, it would make it easier (and more lucrative) for the players to at least stay a few years at home.
Just spitballing, but the article seems pretty legit.
I would think under MLB rules, they would be subject to international amateur signing rules. So there isn't the big money for signing. If they are that talented they would probably rise up the payroll ranks quickly in Japan. Tanaka at 24 is making 4.5 million there. If he had sat out his year, went to the minors here, now as a 2 or third year player he would make no more than a million. When he comes here he can negotiate a higher payday with time enough left for a real good contract. I think they are money ahead because they will rise quicker in Japan and get paid more in the end during the development/pre free agent time.
Anyway, the Japanese owners may be taking heat from the players association. The Japanese players association hates the posting system as the players only get to negotiate with one club. If the MLBPA sees an unfair practice, they sure as hell don't sit down and take it. I doubt the Japanese players association is content with the current agreement.
Anyway, no matter what the rationale for change is, I'm not sure why you're disagreeing that change is likely in the air, it's all over the internet. Plenty of credible publications are getting suckered it would seem:
There could be a big change to the Japanese player posting system this offseason | HardballTalk
Report: Major changes to posting system are in the works - CBSSports.com
Impact of changes to posting system - MLB Rumors Blog - ESPN
Japanese Posting System May Change This Fall: MLB Rumors - MLBTradeRumors.com
This article puts the Angels on Tanaka -- Los Angeles Angels scouted Masahiro Tanaka, Japanese pitcher, according to report - ESPN Los Angeles