CAN Bus and its Termination Resistor
The 120 &Omega; terminators at each end of a CAN bus serve two purposes:

To terminate the transmission line.

To guarantee the bus lines are at the same voltage in the recessive state.



Note that neither of these has anything to do with the bit rate.  The first is a function of the transmission line characteristic impedance.  The drive currents, voltage levels, thresholds, and the like were all decided with the second in mind.