Don't forget that a lot of the discussion around getting the resources for editing was started by someone who wanted that without purchasing the engine.It would be absolutely insane if RTP edits weren't allowed anymore.
While in the past you could get those resources by the separate RTP package, that was never the intention of that package - and Degica has stated in answer that this time, you need to purchase the engine to get the resources.
And that never was different - you always had to purchase the engine to get the licence to make edits of the default resources, even if you could get the resources without that.
I don't know how they will handle it with MV (I'm not one of the testers and don't know more about it than anyone else), but my guess is that without a separate RTP package, you're simply forced to use the export function of the editor to get the resources for edit.
You shouldn't forget: even if there is no RTP, the resources can't be protected when deploying by HTML5. So it would be really stupid to create artificial blocks for access from the editor when a simple project export gets you everything you want.