I forsee they'll make all those libraries and tools free for hobbyists - and maybe even 'less than free' - ie. "We'll send you a free dev board if you download the IDE!".

But if anyone tries to ship arduino code in a commercial product, they'll want royalties.

Or if any microcontroller maker wants to be supported by the ecosystem, they'll also want royalties.

And the royalty levels will be low because there are competing ecosystems of tools - but across such a huge market of embedded commercial electronics, I think they'll still do very well.