it is a private sector system (ARINC/Rockwell) paid for by the industry at paltry cost per member and I cannot imagine them giving up that option, especially for LDOC communications.
SATCOM voice has already probably replaced close to 99.9% of LDOC calls to maintenance, dispatch, medlink, etc. that used to be done on HF. The only time I could see an airline like JetBlue using HF for that is if their SATCOM was unserviceable that day.
Also will this mean that VHF will also disappear for communications in favor of text messages and sat comms.
CPDLC (texting) is now used by all Canadian ARTCC's in high level domestic airspace (FL290 and above). The extent it's used seems to depend somewhat on pilot and controller preference. It's common to only hear an aircraft check on the frequency and that's it. Routing, altitude changes and frequency handoff's all done on CPDLC. At first it was just used by long range international overseas Atlantic and Pacific flights, but now Air Canada and WestJet have started using it on domestic flights as more of their fleets are becoming equipped. Both airlines start taking delivery of the B737 MAX in a year or so and I would guess the CPDLC package comes as a standard option ?
CPDLC uses VHF or SATCOM and even HF in some cases (?) but unlike ACARS messages that are easy to decode, CPDLC transmissions are encrytped.
A4471/14 NOTAMR A2776/14
Q) CZYZ/QCDXX/IV/NBO/E /000/999/4729N08055W999
E) CZYZ WEF 2014 APR 12 1300
CPDLC PHASE 1, 2, AND 3 FOR TORONTO ACC IMPLEMENTED WITHIN HIGH
LEVEL AIRSPACE FL290 AND ABOVE AS PER AIC 15/14.
ONLY THE FOLLOWING DOWNLINK MESSAGES WILL BE SUPPORTED BY TORONTO
DM0 - WILCO
DM1 - UNABLE
DM2 - STANDBY
DM3 - ROGER
DM4 - AFFIRM
DM5 - NEGATIVE
DM6 - REQUEST (ALT)
DM9 - REQUEST CLIMB TO (ALT)
DM10 - REQUEST DESCENT TO (ALT)
DM18 - REQUEST (SPEED)
DM20 - REQUEST VOICE CONTACT
DM21 - REQUEST VOICE CONTACT (FREQ)
DM22 - REQUEST DIRECT TO (POS)
DM28 - LEAVING (ALT)
DM29 - CLIMBING TO (ALT)
DM30 - DESCENDING TO (ALT)
DM32 - PRESENT ALTITUDE (ALT)
DM34 - PRESENT SPEED (SPEED)
DM37 - LEVEL (ALT)
DM38 - ASSIGNED LEVEL (LEVEL)
DM39 - ASSIGNED SPEED (SPEED)
DM47 - SQUAWKING (CODE)
DM55 - PAN PAN PAN
DM56 - MAYDAY MAYDAY MAYDAY
DM57 - (FUEL) (FUEL2) FUEL REMAINING (SOULS) SOULS ON BOARD
DM58 - CANCEL EMERGENCY
DM60 - OFFSETTING (DOFF) (DIR) OF ROUTE
DM61 - DESCENDING TO (ALT)
DM62 - ERROR (ERROR INFORMATION)
DM63 - NOT CURRENT DATA AUTHORITY
DM64 - (ICAO FACILITY DESIGNATION)
DM65 - DUE WEATHER
DM66 - DUE AIRCRAFT PERFORMANCE
DM67 - FREE TEXT
DM80 - DEVIATING (DOFF) (DIR) OF ROUTE
ANY DOWNLINK MESSAGE OTHER THAN THE ABOVE WILL GENERATE A 'MESSAGE
NOT SUPPORTED BY THIS FACILITY' RESPONSE FROM THE GROUND SYSTEM.
It's also already been in use in domestic airspace over Australia and parts of Europe for some time now. There are some LiveATC feeds that cover these sectors and you can hear (or not hear) how much CPDLC is being used.