To start, essentially the problem boils down to this:
In a recent interview, Amy Pascal indicated heavily that both
Venom and Silver & Black were set in the MCU in which Spider-Man: Homecoming takes place in, which is contrary to both previous statements by Feige and another one Feige made just recently saying they were
not connected to the Marvel Ci
nematic Universe. Naturally, this has kicked up a bit of furor in the fan community as to what the hell this all actually means, so I think I'll break down a few facts (and non-facts) that have been brought up in the wake of this recent news.
#1: Does Only Kevin Feige Decide What Is Canon In The MCU?
This is a complicated question. There have been installments in the MCU that have lacked Feige's involvement, such as every entry made by Marvel Television (save for Agent Carter, which is the only MCU property that Feige has personally worked on). The TV shows, however, do appear to have been given Feige's blessing and acknowledgement, including shows that were once being developed as films under his studio, such as The Inhumans and Runaways. However, while he hinted at some kind of crossover in the future, he's never gone out of his way to actively include references from the TV side into the film side. The closest thing to one would be Damage Control, which was both referenced in Agents of S.H.I.E.L.D and currently floating in TV limbo as possibly being its own series before appearing in Spider-Man: Homecoming. To that extent, however, there is one thing of this we can make for certain, and it is that Kevin Feige is not the only person creating content that is canon to the MCU.
#2: Does Sony Have Any Authority Over Marvel Studios?
While Feige has produced all the movies in the Marvel Cinematic Universe, including Homecoming, this case is different: not only his Amy Pascal co-producing with Feige, unlike the one other time Feige has not been the sole producer, The Incredible Hulk, Marvel Studios is making a movie out of a property they do not own. Unlike the Hulk, where Universal retains some distribution rights while Marvel has the actual character rights, Sony still owns Spider-Man entirely, as evidenced by the fact that they can both make Homecoming and also make the Miles Morales animated Spider-Man film at the same time.
What is less clear, however, is whether or not Sony can make films like Venom and Silver & Black part of the MCU seemingly without any actual permission from Marvel Studios. There's not much known about the actual content over what the deal to allow Spider-Man: Homecoming to happen is, but all reports indicate it is essentially a quid-pro-quo deal: Marvel can produce Spider-Man films, and include him in other Marvel Studios films, but Sony pays for, distributes, markets, and profits from the solo Spider-Man films, and (to an unknown extent) characters from each side can cross over to the other, with permission.
In simpler terms, Sony cannot make references to characters Marvel Studios owns without permission.
This, however, does not clear up the main concern with what Amy Pascal has been indicating: actually What this does bring us to is a final question:
#3: Does Sony Have The Ability To Create Films Set In The MCU?
And the answer is: Yes.
Technically.
See, while Sony would need explicit permission from Marvel and/or Feige to use characters that Marvel owns in the spinoffs (such as a reference to the Avengers or Iron Man, for instance), and Feige's current stance seems to ensure such a reference will not happen. Sony can, however, freely as and as much as they wish to, make Spider-Man references. There is absolutely nothing, legally speaking, keeping from, for instance, referencing Spider-Man, or making references to other Spider-Man characters, such as Vulture, J. Jonah Jameson, or places such as the Daily Bugle. As for an appearances by Holland in the spinoffs, which Pascal also hinted at being a possibility in the interview (and THR reported is, indeed, party of Sony's plans for their "adjunct" films), while Holland is not currently contracted to appear in any spinoffs (currently only for two more Spider-Man solo films and both parts of Infinity War), a new contract could happen that would have Holland appear, or a workaround could be in place (direct references to the events of Homecoming, appearances by other characters from Homecoming, or potentially just a visual reference without Holland being physically present (such as a CGI Spider-Man wearing the Civil War/Homecoming costume).
Now, can Feige disavow these films and choose to never reference them? Oh, absolutely he can. No Marvel Studios film is obligated to acknowledge the existence or events of any film Sony makes, similar to how they don't actively reference the Marvel Cinematic Universe's television entries. But could he contradict them? Well, that would be likely be substantially harder. If we're operating under the assumption that each side can only use the other's characters with permission, then it likely is a two way street: if Sony can't use Marvel-owned characters in their films without permission, Marvel cannot use villains such as Venom, Black Cat, or Silver Sable without Sony's permission either. And since Sony clearly consider their films a part of the canon, I doubt they would give Feige permission to actively retcon their entire initiative.
So, while Kevin Feige can say as much as he wishes that the Sony spinoff films are in no way canon, Sony is under no obligation or restriction with trying to connect their spinoffs to the aspects of Homecoming they have legal rights to. And while fanboys and fangirls can argue till their faces turn blue how Sony's films aren't really canon, if Sony has a Spider-Man appear in any of these spinoffs that is identical to Tom Holland's (and possibly even actually played by Tom Holland), you're going to have a hard time convincing the broader moviegoing public that the films aren't really connected.