If you fantasied about not biulding - so after ended building 949A subs, so then start building subs project 881 (Mercuriy). Picture like modern 955 (Borey) submarine, but fore part like modern 885 submarine with 10 650mm torpedo tubes and 16 324mm torpedo tubes for antitorpedo torpedoes. Total 30 modern 650mm torpedoes and 32 antitorpedo torpedoes. And 24 new heavy anti-ship missiles "Bolyd" with speed mach 4.
Now our subs 955 is development from 881 with ballistic missiles instead antiship missiles and other torpedo armament. 885 subs like development from 881 with small anti-ship missiles "Onix" instead heavy anti-ship missiles "Bolyd".
881 project picture:
http://infreactor.org/15402--merkuri...kih-avianoscev