Jim-san will have to do a very very difficult, delicate and maybe painful decision about it, so it's natural he cannot answer us individually. All we can do is to give him the best advices we can make honestly and wait.
My advices are: - 2ch browsers have always been "open" and joined by many ardent users for years, thus they must stay open. It's a community or an ecosystem of their own. Even Jim-san cannot change it. - closed API is doomed to fail in any open web service anyway, so please fail gently. - forcing ads won't work. Let everyone use the API, and just reward (with cash or privileged connection) those who display ads or buy Ronin ; make it incentive-driven. - Mr. Yamashita is a business person, so he acts for his own benefit. Neither ours nor yours. Please face the users... that's why you've always been loved.
Locking out SC and log-soku with closed API? I bet that won't work. I can easily devise 50 workarounds. Please just forget that idea. Let's build nice platform just like twitter or facebook API instead.
Starting from excluding everyone (resulting in oligopoly) is the easiest way to ruin everything. No one would help us. Let's do the opposite.
For example, we can start with fully-open easy-to-use useful nice sweet API and wait for all the developers to use it (and collect the feedbacks to make it better.) Then we can start to restrict it slightly -- eg. we can give everyone 2400 free API access per day (100 per hour). If one exceeds it, the access is limited to once in 30 seconds. Authorised browsers with ads or Ronin can bypass this restriction. (Of course one can bypass it by changing IPs, but that's inconvenient, you know.)
And then we can terminate DAT service at last. Not at first. Make haste slowly. 急がば回れ