Reverse thrust essential?
"...especially open-rotors configured to deliver reverse-thrust braking after landing. This last is more or less an essential capability nowadays."
Is it really? Published aircraft braking distance calculations do not take into account the use of reverse trust and sometimes reverse-thrust use is disallowed for ... noise abatement reasons. The whalejet (Airbus A380) has only the inner two engines equipped with thrust reversers to minimize foreign object damage to the outer engines located away from the runway.