I'll echo what Casiella said. We really don't know what the new motherships will be. Since the new supercarriers basically dumped the logistics side of their role, maybe the new motherships will take that up, with clone bays and corp hangers.
Here's some complete speculation, but maybe it will be like the Jovian motherships were hinted at in the chrons, more a mobile station than a ship. Maybe it could be some sort of mobile POS, fly to where you want it, then eject in your pod and it becomes a pos, complete with shield. Maybe it would have limited manufacturing facilities and everything, or use it as a tower and set up modules around it. Then if it gets attacked and put into reinforced, maybe you can make it a ship again pull in all the modules and fly away before the second attack comes in. I think that would be very useful to the PvE crowd, your own manufacturing facility in deep space, even if it was limited to low sec, it would still be easier to protect than a POS.
Anyway, I guess we'll see.
NOT STEALTH EDIT:
Just had an idea, which probably isn't going to happen, but...
What if Sansha motherships can generate wormholes. And with a quick hop into wormhole space, you can go from Jita to Amarr in one jump. Even throwing on limits like, can only do to sub capital ships, one so much mass, etc, it would still be completely awesome.