With that model removed from the supply chain they presumably think retroactivity to be unnecessary.
Bingo! Making a pressure probe that won't ice isn't that hard - you can put as much heat into it as you want (and pretty much anywhere on the probe you want) without significantly affecting the measurement. The only real limitation is the electrical load on the aircraft, and making sure the heater doesn't burn itself up. Boeing ties air data probe heat to 'air/ground' - switching pitot probes from 'low heat' to 'high heat' when in air to help keep from burning up the heaters on the ground when there isn't any cooling air. TAT probes are much tougher since too much heat in the wrong place will corrupt the measurement - as a result corrupted TAT measurements have remained an issue in spite of repeated redesigns.
IIRC, engine inlet P2/T2 probes (which have occasionally had icing issues, especially the temp portion) get ~500 watts heat, while aircraft pitot probes get close to a kilowatt at high heat.
Of course, that doesn't help with the mud dauber or the taped over static. Sometimes there is no substitute for basic maintenance.
