Not only civil aviation will change a lot over the next 100 years, also military aviation.
All B-52Hs will have been re-designated B-52J since they have had all 8 HP
turbine disks exchanged with new improved turbines - proving a 2% improved specific fuel consumption and reduced smoke emission. Following an 800 pages long report from the Pentagon B-52 committee stating that re-engining would be too expensive.
The F-35 Joint Strike Fighter - canceled in 2024 - will have been re-initiated as replacement for the now worn out Lockheed F-16G and F-16Hs built in the mid 21st century as compensation for the canceled F-35 program.
In Britain the last Canberra PR
.9 will have retired years ago. The 2034 report about Nimrod MR
.4 replacement will be shelved in 2084. Instead of a the report recommendation to replace the Nimrod MR
.4 with a 737NNNG based platform a major rebuilding of the Nimrod MR
.4 into MR
.5 will be taking place - having run for 20 years - with first flight expected next year.