MacOS is going to get a fixed amount of stage time of the WWDC Keynote.
macOS is lined up to:
Kill off 32 bit apps ( how many users have completely cleaned up and prepare for this? )
Kill off QuickTime.
Intro Marizpan.
As partially an representative example of Maripan, kill off iTunes as
a name ( this may get spread over multiple OS. )
https://www.macrumors.com/2019/06/01/apple-wipes-itunes-facebook-instagram-pages/
the fact that early before the keynote, Apple is poking a stick in the hornets nest that is old school, hard core iTunes users means they'll have some explaining to do. That will occupy some substantive time. Probably
one of the major bullet points of the keynote if pre-triggering like this. )
Plus new stuff that isn't Marzipan. (e.g., perhaps new driver framework (more stuff folks will need to migrate/upgrade) , etc.)
So, some large empty void of extra time for a Mac Pro extravaganza ...... doesn't look promising. Multiple Apple software and service moves that impact tons of Apple users (and developers ) probably will get priority. If all Apple is doing is 'kicking the can' to the end of the year they could do that outside the keynote.