A company based out of the US or Europe is going to have a very hard time competing against DJI and they don't exist to the extent of DJI because of that. I don't forsee a US/European based drone manufacturer that could provide what DJI does at a similar price point
If they're outright banned, why should their patent still hold up anywhere in the west? It'd be dumb not to allow someone to take the ip and make their own product. Fire with fire.