Apollo fire control for light units
By and large, the reasons this won't work (or, at least, won't be used) have already been ably advanced. To sum up from my own perspective, however:
(1) Destroyers, even Rolands, are neither intended nor designed to engage in combat with capital units. They don't need that capability to perform their designed functions.
(2) If it were possible to use standard FTL communications channels/installations to do what Keyhole II and Apollo do, then Sonja Hemphill wouldn't have spent billions of dollars and incredibly precious man-years of R&D developing the platforms and the attendant shipboard installations required to make the system work.
(3) You aren't going to be able to fit Keyhole II and the required shipboard hardware and software into something the size of a destroyer -- not even one of the new DD(L)s. As things currently stand, you would be hard-pressed to fit it even into something the size of a Nike, and doing so would require a significant reduction in magazine capacity.
(4) The Rolands were designed to fit a very specific tactical and strategic niche. They were also very deliberately designed not to fit other tactical and strategic niches. They are the fleet's new-generation destroyer, and one of the considerations that went into their design was the identification of capabilities which had to be left out in order to keep them from being pressed into roles for which they were never intended. There is no way that BuShips is going to go back and look at ways to cram in the very sorts of capabilities they very carefully designed out.
(6) The Mark 16, which the Roland was designed around, is still seen as a very significant and useful weapon system post-Apollo. The Mark 16 was never intended to reach out and engage capital ships, and especially not to engage superdreadnoughts. It has evolved into a significantly more powerful weapon than was originally envisioned, and that's just fine with the Royal Manticoran Navy. However, what they were looking for with it -- and what they got -- is a medium-range missile (in an era of MDMs), with sufficient range and sufficient hitting power to deal with other relatively light units (specifically, those lying "below" the wall battle) and to force commerce raiders -- especially commerce raiders -- to honor the threat it represents. The Rolands are intended as scouts, convoy escorts, LAC-killers, additional missile-defense platforms, commerce raiders in their own right, and force multipliers in a strategic sense by providing the RMN with enough hyper-capable platforms of sufficient combat power to cover relatively large volumes of space without tying up CA(L)s and BC(L)s that may well be urgently needed somewhere else. For all of those roles, the Mark 16 is fully adequate as it stands. That isn't to say that it can't be improved upon, or that it won't be, but there is no way that the Navy is going to accept the mass and volume penalties of building the components for Apollo into a unit intended to employ dual-drive missiles rather than multi-drive missiles.
None of this should be taken as a flat statement on my part that Apollo capability will never creep downward into ships smaller than SD(P)s. What it should be taken as is a comment on the engineering difficulties inherent in doing so, on the cost in terms of combat endurance and flexibility for the units in question, and the nature of the DD(L)'s designed role and intended function. And, I suppose, also a comment on the current Manticoran thinking on the viability and utility of the Mark 16 as opposed to the Mark 23 MDM and its sub-variants.