I've been reading somewhere (was it in this forum or elsewhere) that there are plans for all airside vehicles to be fitted with ADS-B. I would have thought that the cost would be prohibitive and that it will take years to happen.
Just in case, though, it may be wise to find out more about this - I'm sure we don't want RB completely swamped by catering trucks, baggage tractors and all the other mobile clutter at airports, so we're going to need a way to filter them out.
Then again, perhaps AirNav could set up a new system called Aircraft TugTrax!
Rod