N_a_B, brainfade on my department, 3 1/2 years was of course the plan (that went wrong by a factor of 2). However if the question of ordering the successor class, and the provision of fit for purpose maintenance facilities had been handled at the right times the issues may never have arisen, I believe back in 2007 the planned post LIFEX OSDs were Van. 2022, Vic. 2024, Vig. 2026, and Ven. 2029.
Asturias, I would put the chances of a 5th D-boat at zero. My choice, however, would be HMS Hawke
as its about time a capital vessel was named after the great man. (Of course Agincourt is available.)