Indiana Jones and Star Wars are already being done by Lego. But generally yes, Basie, I think you're correct.
The licensing would probably bump into what Hasbro is doing - unless there's a price point loophole (some items from Marvel and Star Wars got made by non-Hasbro manufacturers by raising the SRP significantly. Funko Hikari comes readily to mind, those were $80 as opposed to $50 for other licenses, and sometimes licenses are written by price point as well as size/master toy license/outlets/etc. Diamond did a similar higher price point product for its not-quite-Mego figures of various Marvel heroes.) Hasbro has been very protective of the Star Wars toy license in this scale, LEGO's stuff is a construction toy, and Funko's stuff are bobble heads with bases (as opposed to just figures with vinyl heads that turn, as that's a different kind of product with a different license agreement.) I would buy every last Playmobil Star Wars set they made if they ever did it. Indy, well, who knows. It'd be cool but it underperformed last time Lucas/Hasbro/etc. did a big push for it around the time of the Crystal Skull movie.
For 80s licensing, I'd probably look at LEGO Dimensions and anything they did for that could be viable. It seems like it's already been a proving ground - after all, we've already got Scooby-Doo, BTTF, Ghostbusters, and A-Team. Gremlins, Beetlejuice, Knight Rider, E.T., Doctor Who, Goonies, Simpsons, and a few others were licensed for LEGO Dimensions and seem like they could also be good fits. That's where I would place my bets - they've already proven the license holders are willing to do this kind of thing.
I assume Playmobil will want to do anything where there's a key vehicle (as we've seen with most of their US-friendly entertainment licenses so far) with multiple good characters.
Personally, I'd want to make Bill & Ted. Lots of historical figures and heroes that can probably be made with mostly existing parts, a unique vehicle that can be made at a low price point, heroes with very distinctive costumes, also Playmobil George Carlin in wacky future clothing. Like Back to the Future, it allows you to take something new, and reuse lots of old sets with a new license. You can sell Western, Castle, and a few other themes alongside it. Is it appropriate for kids? Probably not. But Back to the Future isn't too far off from a similar tone in terms of some adult themes, albeit with less adult language. If you're not a fan of Bill or Ted, you can still buy Gengis Khan, Joan of Arc, Napoleon, Billy the Kid, Abraham Lincoln, etc. Also Metrocenter Mall from here in Phoenix was used for the San Dimas mall for the first movie, and any excuse I could come up with for a Playmobil Metrocenter Mall playset would be great.
