>>79159271I think the closest we'll ever get to Steven seeing his mom again will have something to do with Rose's room. Remember that the whale in there suddenly spoke in Rose's voice towards the end of that episode, and its been shown to be capable of creating constructs of individuals based on what it can gather of them.
I think that a pretty decent Rose-construct is somewhere in that room, seeing as how it had as long as Rose lived there to gather data of her. In fact I think that Rose's room has a lot of answers to the show, and Steven just has to come to certain realizations of his own before he goes there to find them out.
For example, Greg losing his cool and trailing off about the gem war "It's not like I was there", sweating bullets and everything, seems really uncharacteristic of him. I think that Rose used the room to show Greg what she was involved in, and that at some point Steven will use it to show him and us, the viewer, exactly what the war was like without the gems sugarcoating/refusing to talk about it.
Also think it's highly likely that more will be revealed about Lion and what's in his mane either through the room directly, or something in the room tipping Steven off to it.