Although Kinzhal is supposedly out of production.....yeah I think they will just keep Osa
Perhaps they could unify the design and use TOR-M3 missiles at sea?
Just use the drop in vertical launch tubes without the naval rotary arrangement to increase the numbers of ready to use missiles.
The missiles themselves are cheap and making a few extra 10,000 for naval use will make production even cheaper overall.
BTW to be of any use all future new and upgraded vessels need Sigma to be installed to share data and provide communications.
Inclined launch bins for UKSK launchers would not be that expensive and the result is the withdrawl of an old missile system that would need a separate set of maintainence and handling tools to keep in service.
Standardisation really only works if it is fully implemented as quickly as possible.
Maybe replace Osa and the AK-630s with Palma.
Palma is low cost alternative... they want to protect these old ships so I say Duet guns, Pantsir-S1 gun/missile systems, and TOR-M3 based missiles in new compact stealthy mounts.
The enormous array of sensors and antennas can be consolidated into a few systems to reduce weight and improve performance.