They might be contractually obligated at this point... and those projects are less risky because there are fewer fan expectations for said properties.
A Sinister Six movie might tie into the MCU by being about the first super villian team-up, playing it like a heist movie where the villians win... and then the Avengers (or someone else) have to track them down in a bigger, MCU directed movie later the same year.
They might go the "Agent" Venom route and have it be about a government agent using the symbiote to track down and stop a rogue villain (before giving in himself).
Still don't know how they'd do a Black Cat movie though.
A Sinister Six movie might tie into the MCU by being about the first super villian team-up, playing it like a heist movie where the villians win... and then the Avengers (or someone else) have to track them down in a bigger, MCU directed movie later the same year.
They might go the "Agent" Venom route and have it be about a government agent using the symbiote to track down and stop a rogue villain (before giving in himself).
Still don't know how they'd do a Black Cat movie though.