MAXON was uploading the R19 videos to Vimeo a week ago. Recall, by mistake the Sound Effector video was public briefly. This means the announcement is imminent. This ties in what what they've done in the past and I can't think why they would change.
It could be MAXON's Tuesday around midday rather than Monday 31 July. This gives them a day an bit back at work after the weekend to finish preparing their site. Whenever it is, it's very close.
Yup, the main feature of R19 will be a free render engine. Recall that Cycles for Blender is also free but you have to pay for the bridge to C4D. You're paying for MAXON's time to integrate it. Some will love it but for others they will still need to use the existing render engines as ProRender won't support C4D's material system 100%. Some of the shaders and special f/x won't be supported. Plus a list of other stuff as well.