I have to say, I've got more than a passing curiosity about what is going to happen to the Raven fleet come ilClan time. Right now, they have far and away the most powerful navy in the Inner Sphere...when it's all active. However, they are having a hard time justifying the cost of keeping that huge fleet active with nothing to do with it. So, something will have to give and I doubt the Raven fleet will keep sitting around looking pretty for ilClan.
Do they try to start conquering more systems? Sounds nice, but unless all you want to do is blow them up, you need ground forces to hold planets. A warship fleet would be fine for blockading someplace, or even raiding to steal some of their stuff, but you can't really claim and hold a planet with a space ship. Heck, they are already having trouble managing the few worlds they have already taken or been given, how are they going to raise the tempo enough to give three full stars of Warships something to do? Being able to show up in orbit and broadcast, "Hey guys, you all belong to the Raven Alliance now," isn't going to cut it.
Do they lend/sell some of them? Probably not to their neighbors, who would likely end up turning around and using them against the Ravens before long, but maybe to the Sea Foxes or the RasDom. The Bears especially have most of their eggs in one big basket (or two, if the Leviathan III comes online), and could use the ability to station at least SOME naval power in different places across their empire. They have a whole lot of space to protect and one warship just can't be everywhere at once. They also seem to have abundant 'resources' which they could trade to the Ravens. They have Mechs, AeroSpace assets, Raw Materials, pretty much anything other than trained warriors, and even those might be possible with some sort of contrived trial. The Sea Foxes also have resources, and might not be averse to picking up a couple more hulls they can convert for Aimag duty.
Do they go to war with someone and get many of them blown up? That's going to be a little tough to manage. Their two neighbors have only three warships between them, two of which are corvettes, and they are unlikely to be more than a speedbump in a fight with even a single naval star. The FedSuns and the Combine just don't have the naval power to do much damage to a real naval star. So, who would they fight? The Falcons and the Wolves are really the only powers that have something approaching a credible fleet that could seriously damage or kill one of the Raven's naval stars. Unfortunately, they are on the other side of the Sphere. Heck, even if they somehow managed to hitch a ride on the 'Come conquer Terra...again!' bandwagon, the Republic isn't exactly flush with warships. And really, how many times can the magical SDS systems be resurrected and cripple yet another fleet. That system has been destroyed at LEAST three times already, how much can really be left!? Maybe if you could somehow convince the Bears and the Ravens to get in a fight, you might be able to erase some of the Raven fleet and the big Leviathans at the same time, but that seems like a stretch. They have always been friendly towards each other, and they are separated by the whole of the Combine. Why would they bother fighting each other?
I guess there is always the boring old 'stick them back in mothballs' option, but I find that unsatisfying.
So, what do you folks think might happen with the fleet?