The only other person in my family who likes retro-gaming is my 9yo daughter. She's taken quite an interest in my old machines but not to the extent she'd actually want to keep them. I'll leave everything to her as she does have a grasp of which bits are worth good money, so it'll raise some cash.
I reckon the only thing she'll keep is the tabletop Astro Wars game as she knows what it means to me (it was a gift from my Dad in '81) and she loves it too.
Regarding museums. I know someone who works as a curator at a museum of technology. He says they get so much stuff donated that they're really not interested unless it's super-rare. If the bequest comes with instructions (such as the collection is not to be split), they refuse it. If not, most of it ends up in storage or sold on.