hello,
I'd wish to have more variable memory.

This is now limited to 15kByte by RobotC, but 30 kByte or more were desirable (although you'll nevver may have too much of this).

If there should be a lack of variable memory space, because the firmware, the RobotC virtual machine, and the code memory space need too much of the 64kByte RAM, one could extend the variable memory (stack, heap) maybe by I²C-SD-Cards-extenders, what is not supported nowadays (as far as I know).

Is there already sth planned?

There are no current plans to increase available user variable memory beyond the current 15K.