Sony isn’t the one making creative decisions on the movie tho. Kevin and the rest of Marvels producers make the creative choices. So setting up venom, a different property at a different studio, wouldn’t be in their minds.
I'm sure theyve already had talks with Marvel about using Venom in the MCU.
Being that Venom is probably Spidermans most popular villian,you can guarantee Marvel already knows whether or not they will have the rights to use him at some point.
They need to know so they can build the story accordingly. Official announcement should be coming soon.