In another talk, Stephen Rostedt from Redhat explained the RT Preempt using his presentation from 2007 with updates in. Thomas Gleixner was there helping with explanations about how things have changed since 2007.
At the end, there was a question to Thomas Gleixner "Do you consider RT Preempt will make other solutions like Xenomai obsolete?"
"Yes, I do believe so" was the reply.
The answer made me smile since it makes clear what is the mindset of people like Thomas: they love challenges whatever the complexity!
I will not bet against him but moving the Fully-Preemptible Real-Time Linux kernel one step further means HARD real time. The main problems against is the kernel is too big and all we know bugs are out there. Xenomai and other solutions like RTLinux/RTAI are based on simplicity so bugs can be minimized. RTOS vs GPOS is all about determinism and RTOS can achieve this because the code is small enough for verification.
RT Preemtp has brought some sort of revolution with design changes like IRQ threads. IMHO making the RT Preempt hard real time could just be achieved with another revolution which would make happy professor Andrew Tanenbaum (and Linus a bit grumpy).