Venom Isn't In The MCU (Right Now)
Ultimately, there's no actual evidence that Venom should be considered part of the MCU. Leaving aside the bevy of confusing statements from Kevin Feige and Amy Pascal last year, more recent comments have asserted that Venom and the other spinoffs are a separate universe. In July, for example, EW stated that Venom is "a separate world from last year’s Spider-Man: Homecoming." They additionally stressed that the film is "not part of the deal between Sony and Disney that allows Tom Holland’s Spidey into the Marvel Cinematic Universe." Joe Russo, co-director of Avengers: Infinity War, was asked by one fan whether or not Venom should be considered part of the MCU. He gave an unequivocal response; "No, that's a Sony property." It's important to note that Russo was fielding a lot of questions, and throughout the discussion, he was very wary indeed of spoiling anything. Still, it's clear that, so far as Joe Russo is concerned, Venom is not set in the MCU.
But one of Kevin Feige's replies last year is particularly interesting. In the midst of all the confusion, there was one interview where the Marvel visionary seemed to give a straightforward response. "Right now, Spidey is in the MCU and it's just Spidey," he observed. Feige is a master of language, and his word-choice is always extremely precise. The fact he chose to use the phrase "right now" is notable. It suggests that things could change...
Venom is Made to be Retconned into the MCU
Sony seems to be hoping that Venom - and, by extension, their entire Spider-villain universe - can be retconned into the MCU as part of a later deal with Marvel. That's reportedly one of the major reasons the studio designed Venom as a (hard) PG-13 franchise rather than aiming for an R-rating; Sony hope that Spider-Man and Venom can face off further down the line. Insiders have continually hinted at the possibility. "There may be some day where you see them together," Amy Pascal commented. "You never know." Director Ruben Fleischer recently told Screen Rant that he thinks some sort of crossover is inevitable. "We want to see these characters interact," he explained. "As to the semantics as to where it takes place it's not for me to decide but it feels like there's a way everyone can co-exist in it in a satisfying way."
Venom is set in San Francisco, a location that's only previously appeared in the MCU in the Ant-Man films. Had Venom been based in New York, the risk of contradictions would have been far greater. The plot is relatively self-contained, lifted mostly from the Lethal Protector comics, and thus it would work just as well in the MCU as outside of it. The only possible issue is avoiding any alien skepticism, given extraterrestrials have been common knowledge in the MCU since the Chitauri invasion in The Avengers. Looking ahead to the rest of the franchise, the lack of overlap between Marvel and Sony properties does mean they could co-exist quite easily; Sony isn't considering a Vulture movie, for example, and Marvel doesn't have any plans to bring Jackpot into the MCU.
Some plot rumors for the rest of the Spider-villain franchise even point towards this. In August last year there were reports that the (now-canceled) Silver & Black was going to feature a Norman Osborn cameo, but using a voice actor so Marvel could cast someone else down the line. If true, that implies Sony wanted Osborn to become a possible link between their Spider-villain universe and the MCU. Meanwhile, a recent article by Variety raised the possibility of even more connections between the Sony films and the MCU down the line; they mentioned Sony hoping to use "other members of the extended Marvel Cinematic Universe." That statement was made after a thorough and comprehensive range of interviews with Sony insiders, although it is possible that it's editorialization on Variety's part.
The Future Of Sony, Spider-Man, Venom & The MCU
The key thing to remember is that, at some point, Marvel and Sony will have to sit down at the negotiating table again. Tom Holland is only contracted for six Marvel movies; a Spider-Man trilogy, Captain America: Civil War, Avengers: Infinity War, and next year's as-yet-untitled Avengers 4. That's presumably the limit of the current agreement between the two studios, and once it's come to an end, they'll need to decide together what's next for the wall-crawler.
Should Venom and the Spider-villains franchise prove to be a success, Sony won't even need to worry about rebooting Spider-Man again in the event the renegotiations fall through; as the leaked emails confirmed in 2014, so long as Sony is releasing any movies related to their 900 Spider-Man characters, they retain the rights. That means the studio hopes to be in quite a strong position, and Marvel could be forced to retcon these films into the MCU in order to continue using Spider-Man. Only the success of Venom will tell.