Regarding FIA boundaries. I think they were established to indicate a changeover point from one frequency to the next for full reporting procedures. If all aircraft were on, or required to be on, the same frequency, then the boundaries would still be useful. But pilots are not on the one frequency anymore. So, other than providing a very, very rough guide for approximate radio coverage, what use are they now? And after NAS comes in, the frequency variations will be even more pronounced with some aircraft on VFR chat freqs, others on Class E, others on CTAF, each with different radio requirements. The frequency each aircraft will be on will be dependent on their altitude, position, configuration, intentions, etc. So what information would you expect to receive from still having the boundaries marked, and how dependable could you expect that information to be? Just my thoughts, but after NAS they will be pointless. There'll be no boundary for a frequency to indicate and VHF radio range will do as it has always done and improve with altitude.
What the lines do now is indicate very well what frequency to call departing a particular aerodrome, needing assistance or not; you will be in range of the frequency; you will get to talk to an ATC, the right one for the area.
Without lines, it will be hit and miss; no value in the change. ERC-L is loosing the lines; isn't that an IFR (who still need the right frequencies) map?
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