Well that is the question... I personally think the only reason to make the UKSK-M able to carry SAMs is because the biggest SAMs they want to carry wont fit in the Redut launcher tubes... which are designed to carry the S-300 sized missiles (ie the big 250km and 400km ranged S-400 big missiles).
I would suspect that the S-500 will be bigger than that like the larger S-300V missiles.
The question therefore is... is the S-500 able to fit in the UKSK launch tube... I suspect not because otherwise why not just add extra UKSK launch bins to carry them as well... with the added bonus that if it is not expected to be WWIII and the intended opponents wont require S-500 missiles then you could carry extra land attack, anti sub, or anti ship missiles instead.
The thing is that with the SAMs in question.... we have the tiny 9M100 missiles as used in the S-350 land based system where either standard 9M96 missiles as used on the Redut can be used one per tube or 9M100 missiles can be used with four per tube... there are 12 launch tubes in the system so either 12 9M96 missiles in any combination of 50km and 150km range missiles, or four missiles per tube for the 9M100 in any combination... so 12 tubes could carry anything from 12 x 50km range missiles, 12 x 150km range missiles or up to a maximum of 48 x 9M100 missiles or any combination.... 3 x 150km range missiles + 3 x 50km range missiles and 24 9M100 missiles etc etc.
The thing is that the length of these new UKSK-M launch tubes is going to be at least 10m and possibly more for the S-500, so one launch tube has enormous volume in terms of width and depth so even if you assume that one UKSK-M tube that can hold a missile wider than the S-300 missiles, which means it should be able to hold 4 x 9M96 missiles and therefore also 16 9M100 missiles it is still a terrible waste of available space... and what value is there in carrying 4 of the 50km range 9M96 missiles in the tube when the 150km range missiles fit in the same tube.
Surely it makes sense to stack them... these are all designed from the outset to be vertical launch missiles, so having a separator that ejects itself with the last missile in that layer to expose a second or even third layer would improve efficiency and make the smaller missiles more practical and useful.
You might get only one S-500 missile in a single tube, but that is OK... how many satellites do you need to shoot down?
S-400 250km range and 400km range full sized missiles might only fit one to a tube as well, which is also OK because they will mainly be carried by Cruisers and Destroyers and Carriers to defend groups of ships rather than just the ship they are on.
The 9M96 however should allow four missiles per tube per layer and the bigger missile might allow two layers for 8 missiles per tube, while the shorter range missile might allow three layers per tube for 12 missiles per UKSK-M tube.
The 9M100 should therefore allow 16 missiles per layer per tube, with perhaps four layers per tube meaning 64 missiles per tube... which would be valuable for dealing with swarm attacks as these are IIR lock on after launch weapons for CIWS self defence...
These UKSK-M launchers might only be carried on Destroyer and Cruiser size and larger vessels, and I suspect because of the depth of deck needed for these launchers they might retain Redut launchers in shallower areas of the ship just to fill up some space and add capability.
They might integrate TOR type missiles and Shtil type missiles into the UKSK-M launcher and they might have a Redut-M launcher that does too perhaps.
For all we know the UKSK-M might add URAN and other weapons too... like Medvedev etc etc.