that's indeed the trend, i.e. put a small RTOS core along with a normal CPU for non-real-time tasks, in the past it's done on two boards: one is a MCU another i

that's indeed the trend, i.e. put a small RTOS core along with a normal CPU for non-real-time tasks, in the past it's done on two boards: one is a MCU another is a typical CPU, now it's one one, very important for where RTOS is a must, e.g. robotics. How the CPU and MCU communicate is a good question to tackle, typically chip vendors provide some solutions, I think OpenAMP is for this.