Release some of the new APIs for free (not user-facing features) can only improve the situation. Currently, hardly any developers use them because it limits their software to an even tinier market. So this money's wasted, unless there's reason for developers to use them. And the only way that's going to happen is to make them more widely available.
Releasing those APIs for other systems makes the money the subscribers have spent with you actually do something, rather than nothing, and so it's better value for them.
"It seems that lots of you who are pushing for RISC OS to be freely available are those who have never paid for anything from RISCOS Ltd. Do you never pay for software, or is it just RISC OS that you don't want to pay for?"
I pay for lots of software; when it's worthwhile. RISCOS Ltd.'s product is expensive, and doesn't run on any hardware I own.