Cruise torpedos sound a likely dvelopement as it is the one location where topedos have and advantage over beams, in that they can be very long ranged, the only problem of course is that they would be easily shot down without a subspace drive, and to expensive for most engagements with one. however, if you have a few torpedo bombardment ships (probably converted old cruisers), and a faster torpedo, they would be useful in some situations.
However, I think that a better use for such vessels would be as fighter carriers that stay out of battle, but allow the destroyers to do away with their fighter bays, and carry even more weapons (or just a reasonable number, in the case of the Hecate class).