Believe it or not, even in U.S. courts you need a better reason to sue someone than "If they stopped doing business, I would do more business." You actually have to prove (or, rather, plausibly allege and then prove) that the business they're doing is not only coming at your expense but through unfair, unethical, or illegal means.
That, at least, is the bigger theory behind a lot of the nitty gritty in intellectual property law: It's not just a matter of getting in on someone else's action, it's the capacity for doing so to damage the potency of the original. To use a relevant example: When DC Comics went on a lawsuit-filing spree to eliminate characters they saw as Superman rip-offs put out by other publishers (most notably the original Captain Marvel - "Shazam!" version), the impetus claimed behind their actions wasn't (officially) only that the other publishers' creations were getting bought instead of theirs - it was also that the similarity could confuse potential buyers and leave DC's brand unfairly vulnerable to association with whatever other publishers decided to do with their DC-esque publications.
More relevantly, this is why studios in the "Cinematic Universe" game tend to be so stingy about what gets to show up where and when. It's not just one brand to protect, it's dozens of smaller individual brands comprising a shared identity - and everyone in charge of each individual facet wants to makes sure that nothing gets tainted by association with anything else. That's one of the reasons why Marvel Studios has thus far only let their three separate development tracks (films, broadcast TV and Netflix) nod in each other's direction and share minor worldbuilding details. while otherwise sharing a respectful distance. It minimizes the impact a creative decision made by one track can cause unwanted associations with another.
T he upcoming Marvel feature Spider-Man: Homecoming represents the grandaddy of the modern Cinematic Universe stepping outside of its studiously maintained comfort zone for the first time since they started; having entered into a kind of shared-custody agreement in order to make one of their marquee characters available for crossovers. It's meant to be a mutually-beneficial arrangement: Sony gets the money-printing MCU branding for the latest reboot, while Marvel gets to use Spidey in crossover events like Captain America: Civil War and Avengers: Infinity War to fill in the previously-vacant "wisecracking teenager" spot in their expanding menagerie. But it's also a bid for Marvel to exercise a greater deal of control over the Spider-Man franchise, which is one of its most popular properties in terms of merchandising (Marvel controls the merchandise revenue for all characters, even ones whose movie rights are not owned by parent company Disney).
Officially, Sony is still producing and overseeing Homecoming, with the co-production arrangement mainly allowing for audience-luring Cinematic Universe tie-ins. But it's widely believed that Marvel-proper has exerted considerable influence on the production in order to protect their investment, and we probably won't know exactly how much of Homecoming's new take on the Spider-Man mythos happened at each studio's command for quite a while. While it's at least possible for Marvel to exert a measure of control over Homecoming and use Spider-Man to their discretion in team-up features, Sony is holding fast to the actual movie rights to the character and his expansive supporting cast of villains and allies - which are now being mined for a series of spin-offs, effectively creating their own "Bootleg MCU".
It's that plan (which thus far is set to include an R-rated Venom movie starring Tom Hardy and a Black Cat/Silver Sable team-up vehicle helmed by Gina Prince-Blythewood) that places Marvel in a new situation. Although these movies won't be part of the MCU, it's almost certain that connections to at least Spider-Man himself would be at least implicit. Venom is potentially recognizable enough on his own to support a feature, but Silver Sable and Black Cat are the definition of C-list supporting characters - a pair of would-be love interests from Peter Parker's 70s/80s "playing the field" phase who can be accurately described in shorthand as "Shiny Black Widow" and "Glam-Rock Catwoman." Of the two, Cat is probably more recognizable given how heavily Marvel has merchandised the cleavage-baring bombshell over the years, but neither one has a particular strong identity outside of "person who knows Spider-Man."
- Spider-Man: Homecoming (2017) release date: Jul 07, 2017
- Venom (2018) release date: Oct 05, 2018
- Avengers: Infinity War / The Avengers 3 (2018) release date: Apr 27, 2018