What would of happened if Mapleshade's kits had never died?

It all depends on what would have happened after.
Example, whether of not she AND her kits would have been accepted into RiverClan, of just her kits, of neither.

If her and her kits were accepted into RiverClan and her mate didn't stab her in the back like he did, I'm sure she would have found happiness.

If just her kits were accepted and she wasn't, then maybe she would be happy for her kits, but bitter to RiverClan. And maybe she would have refused and taken them to be rogues with her.

If both were refused, I'm sure she would end up just as bitter as she is in her story, except her kits are alive. I'm sure she'd still take revenge somehow.

Anyway, I hope that helps. :)