I agree cart witnessing will be first, probably will go on for many months before door to door resumes. We may see cart witnessing (masked up) begin in late summer or early fall. I expect door to door won't happen until 2022.
Maybe they'll use the 2022 Memorial campaign as a springboard to restart D2D? JWs will be rusty after 2 years, so start with an easy "here is your copy of this invitation, goodbye" presentation.
I think maybe KH meetings will resume in some areas around the same timeframe (6 months or so from now), but with reduced capacity. Maybe 1 or 2 field service groups meeting in person at the KH at one time, seated far apart from each other, and the rest of the congregation tied in by Zoom. Then rotate the groups.
100% normal, all KH meetings at full capacity and usual unrestricted D2D, maybe some time in 2023.