Kirk Cousins has an option out year with Vikings next off-season. After that, he and Vikings would be locked together for two more years as the salary gets guaranteed for 2022 as well. If Vikings keep him, they would have 31 million and 45 million cap hit in next two years, so there's a chance Vikings could like to trade him.
Vikings continue to lose talent and his contract would constrict them in next two years if they keep him, and they'd be forced to let more players go. So there's a window next off-season where both may go different ways.
If Colts like him, he might be one of the QBs in their mind.
Trade for him and sign him to a contract you like, and see how it goes.