It depends if the wire was spliced into, or cut and redirected. If the wire is an output from the cluster and the wire was cut, and the other end (non cluster end) connected to the ETB Speedo then one would assume it would not work.
If you splice into the output, I would expect all the other components to work as expected (wipers, radio, DME, cruise control and on-board computer). If you cut the wire and joined, then they wouldn't.
Similarly if you spliced into the input, everything else should work - but only if the instrument cluster is still in the circuit. If you cut the input, the output wouldn't work.