There are two forums here labelled "Drivers looking for teams" and "Teams looking for drivers"...
As long as the registration window for a race hasn't closed, teams can add crew and drivers to their registrations. Usually the windows close a few weeks before the race.
So your "B" point isn't true and I'm not sure where you read that teams can't add people due to COVID; Teams still accept new members up until the reg window closes, you just have to find one (see note about correct forum location above). Regarding your "A" point, that's totally up to you. There certainly are people that are taking the entire year off, but there's also enough people registering for the races to continue as long as they aren't cancelled.
1989 Merkur XR4Ti: Project Merkur Space Program - Wins: Class C - Colonel and the Sinkhole 2023 | "Heroic Fix" The Pitt Maneuver 2023 | "Halloween Meets Gasoline" The Pitt Maneuver 2022
1980 Dodge Challenger: Most Extreme eLemonAtion Challenger (Rust Belt Ramble 2021 Dishonorable Mention)