On 5 July 2016, Svyatoy Georgiy Pobedonosets, a Project 66BDR/Delta III class submarine, returned to its base in Vilyuchinsk after a combat patrol.
It is quite remarkable that these submarines are still in service--K-433 Sv. Georgiy Pobedonosets was accepted for service 1980, so it is 36 years old. Even accounting for the fact that she spent most of its service life at a pier, she is an old submarine. The R-29R missiles are getting old too, of course, but they are probably replaced regularly. The Soviet Union produced a lot of SLBMs, so Russia will not run out of missiles for quite some time. We know that there were 4.3 missiles produced for each R-29R launcher, so at some point Russia had almost 1000 missiles of this type. Even though several hundred were probably expended in flight tests over the years, it should be possible to find enough missiles to put on the three Project 667BDR submarines that still remain in service. And they seem to be in good shape - K-223 Podolsk launched its R-29R missile during the exercise in October 2015.
Delta III submarines will probably retire after new Project 955 Borey submarines take their place in the Pacific. But there are plans to keep at least some old submarines in service -- Ryazan has been undergoing overhaul and will return to the fleet in some capacity.