Looks like a good plan to me. Trading off the old version of Khinzal (Tor) for a pair of Shtil VLS bins is a plus in my book, and I'd happily lose the 2x RBU-6000 if it meant getting an extra UKSK bin in return.
Regarding constructability, there will be a lot of available depth in the aft superstructure adjoining the hangar with the removal of the Khinzal bins and the RBU launchers (and their associated reload handling systems and magazines). Especially the RBU - those things pack a lot of HE into a small space and the magazine is deep in the ship and armoured to protect it (taking a hit in that chamber and detonating the reloads would 100% result in a dead ship). Remove these systems and cut away that entire section of superstructure and you'll have space to accommodate a UKSK and Shtil combo.
In any case, it looks like they are retaining the other Tor structure fwd of the hangar/aft of the crane, so some SHORAD capability is retained for anti-missile defense.
It's a pity about losing the twin 533mm rotary torp launchers, but the UKSK can carry 91R1/91R2 rocket-torpedos so the ASW capabilities are enhanced in terms of range and reaction time. Paket makes a great addition, and doubling the allotment of Urans is a bonus.
The area behind the 2nd funnel was made available on the Shaposhnikov by removal of the crane and FRC. It strikes me that this would be a good place to locate containerised systems when needed, eg extra Kalibre launchers. I expect the area below this platform is engine room, so forget about locating any permanent VLS bins in this area.
Yep. good plan. Now make it happen...