I hear there's a hell of a time trying to get likeness rights for the Bond actors.
RE Harry Potter, if Fantastic Beasts 2 couldn't kill the franchise nothing will. But while I'd love Potter minimates I'm not gonna lie I'm really glad Lego got to it. I absolutely love the castle builds. LOVE them.
It's kinda hard to think of properties that have wide appeal and could sustain a collectable minifigure line for more than a few box sets. Ask me about 6 years ago and I would've said Doctor Who, but recently I haven't heard anyone really give a damn about it. I can't see a world in which DST gets Star Wars anytime soon. Steven Universe has a massive fanbase and would make for great minimates, but there's not a massive character pool and there's little to no variation in the characters to have more than two or three box sets. Though I'd love to see DST have a bit of brand melding and make vinimates with some small amount of articulation (Like Godzilla's) for the Diamonds and the Fusions while making minimates of the rest of the cast.
Over in video game land I could see God of War killing it as well as Smash Bros (Again there's no damn way that's happening though). Actually thinking about it, games may be the most fertile ground for something that could carry for a while. HALO did reasonably well if I recall correctly. COD would just be generic soldiers and Lego has Overwatch (Which I am slightly sad about since they really would be better as minimates) but nobody is doing Final Fantasy right now I don't think. Metal Gear doesn't have a toyline either. Would either of those be able to sustain a line? Ehhhh... Final Fantasy maybe and Metal Gear prolly not. But I still say God of War. Kratos has many different armors and weapons that could be thrown in so it's not like we'd be getting the same look over and over. Hell they could even throw in Cod of War in one of the sets. Then we'd have all the various gods and monsters and they could honestly make this waves and not box sets. Is it likely? No. But it does have potential as a multi wave license.