One can always hope. I am waiting for about 15 years for some kind of realtime processing (audio) becoming possible on Linux. The kernel is certainly capable of doing quite well now that for example preemption during system calls is possible (Big Kernel Lock gone), there are realtime scheduler policies and drivers are behaving most of the time.. a lot of effort has been put into this during the last years, for example by kernel developer Ingo Molnar and other enthusiasts.
But no one can say for sure what"s the matter here until there are proper tests done on the board, with recent realtime or low-latency enabled/configured kernels. The gpu/driver with its possible high bus demands is the big if. IF designed and executed properly, it should work. But don"t just expect it, or you may be disappointed, because this board and SoC has clearly not specifically designed for realtime processing, but more as a small low-power HD media player and OpenGL-engine under linux control.
For games and video, it just doesn"t matter this much.
Check out the XENOMAI project, it's available for ARM and plays with recent linux kernels, it has a realtime model for drivers and threads which could possibly be used for controlling GPIO, timers, ... on the Pi, running below the kernel level, as a minimal nanokernel beneath catching some of the interrupts (Depending on getting enough hardware specs to implement it).
It is well designed also for industrial applications, maybe got a too complex model to use for education? But there this a set of Xenomai skins mimicking traditional RTOS APIs, it could be helpful for learning and studying different options.
Integrating Hard Real-Time into Linux
All the best, Marcus