Air carrier Captain reported experiencing GPS jamming; with both GPS functionality never returning on the flight. The GPS jamming made flying over the North Atlantic complex and the flight crew had a higher fuel burn than expected due to the lower altitude.

Narrative

I was the flying pilot on the first half of OMDB - ZZZ flight; our relief pilots were on rest to work the second half. Upon entering OEJD FIR we followed GPS interference guidance from the FM (Flight Manual) and pilot bulletin. Approaching KITOT we lost both GPS systems with associated EICAS messages as expected. We communicated with Dispatch who asked for notification when GPS status returned as they were tracking it. On this flight we never got our GPS back and Dispatch was advised throughout.We reviewed Oceanic NAT HLA (North Atlantic High Level Airspace) and PBCS (Performance-Based Communication and Surveillance) airspace guidance and confirmed we met the requirements for RNP-10 navigation and entry. Our Aircraft X still had multiple LRNS (Long-Range Navigation Systems) capability but limited us to RNP-10 with associated time limits per tables in OpSpec (Operations Specification). My First Officer had experienced the exact same situation on his previous flight. I later learned that one of the relief pilots also had not gotten GPS back on the same routing. In the past I had it return to operation so this was a first for me. We were planned on a random route for Atlantic crossing at FL360. We determined we would have to operate below PBCS airspace and would request FL340. Free text annotations of GPS failure and the RNP-10 requirement were included in our Oceanic request with Shanwick. At the time we had not logged into CPDLC; normal for this portion of the route; but thought it was functional; ADS-B was INOP per an EICAS message but ADS-C was working as far as we knew and ACARS was working. NAT DLM (Data Link Mandate) guidance requires CPDLC and ADS-C for PBCS airspace Dispatch and entry; but Dispatch only for NAT HLA airspace outside of PBCS airspace; so we were good to go at our requested altitude even though CPDLC ended up being nonfunctional.Our 90-minute Shanwick Oceanic request time was just after our schedule crew swap for rest breaks so I briefed the relief pilots on our status and went on break. Noting that our crossing was going to be lower than planned I asked them to manage fuel to project us at ZZZ with 15k - we were currently showing about 16.5k for arrival.After break I came up to learn that we were restricted to FL310 by Shanwick Oceanic Control for crossing and that fuel had become a bigger concern for them. The relief pilots had coordinated a more direct routing after coast in with Dispatch and ATC had planned options for fuel stops at nearby ZZZ1 or ZZZ2 if required. Once in radar contact after coast in and able to climb for fuel efficiency; the projected landing fuel showed at or above the 15k again. Upon debrief I explained to them FMC tools that could be used for more accurate landing fuel projections - basically that the FMC was giving an expectation of landing fuel for staying at FL310 until ZZZ and that they could have input a planned coast in climb altitude to allow for a more accurate landing fuel projection. I verified with them that our worst ANP was ANP 6.0 which was well within tolerance for NAT HLA operations.ATC kept us high for fuel efficiency and as direct as possible to ZZZ which mitigated the need for a fuel stop. ZZZ Approach did question if we were minimum fuel and we advised that we were technically not with 16k fuel onboard.GPS jamming is a certain threat to multiple aspects of our operation and creates complex scenarios for crews to manage. As a minimum; fuel planning on this route should be incorporated with the expectation that GPS will not return; which has been the recent norm; and that lower North Atlantic crossing altitudes will be required. Full discussion with North Atlantic ATC agencies should occur for their complete awareness of the issue; our navigation capabilities and the importance of altitude selection for fuel conservation. I say this because the relief pilots advised that ATC asked for verification of what systems we had for navigation and that a partial reason for the lower altitude was loss of CPDLC; ADS-B; and concern over our navigation performance. I called Dispatch on landing and explained that GPS not returning will require lower NAT crossing altitudes and that fuel needs to be planned accordingly on future flights. He said he would plan the next flight based on my information and submit a report from his end on the situation. I tried to capture a complicated scenario in minimal words.