As already partially confirmed the gun and/or missile CIWS and the universal VLS are likely, though I have a hard time picturing where the universal VLS would fit on the Sovs.
VLS could be fit where the Shtil launchers were placed. Given the Shtil launchers penetrated the deck quite a bit (due to underdeck rearming/arsenal mechanism) a VLS could fit there quite handily.
The question I'm curious about is how many VLS could fit on the Sovs as well as 051B, assuming they do get fit onto them.
Also, the question is whether the Navy would have the foresight to arm them with the universal VLS or merely the 054A's HHQ-16/VLA compatible VLS, which would make the ships somewhat less flexible in role.