Thank you, very interesting.
On Twitter, they are just opinions, Syed Jafri states:

The biggest assumption there is that other voters do not have overlap in their voting.

More casual users like me are unable to make educated votes on 30 candidates. JSun exactly knew his 20 candidates, being here for a while I'm willing to vote for maybe 5 people, and until recently I've used my little vote for only 2 candidates, which recently I found are inactive. I think the assumption is sound.

Edit: 12149 votes without overlap? - Mr Jafri?

Much more interesting is the link to simulation on eosauthority. As of now, only 2 in the top 21 would drop below, although the order in the top 21 would be significantly re-shuffled. Some producers, like truststaking would need just 5% more votes to make it to the top 21, but now he needs 150% more votes. Overall, in the simulation changes in the order are quite small, but I would expect them to be larger if 1t1v would be a real voting protocol.

1t30v amplifies the authority of big holders like A in my example, so they are and will be opposed to changes. The only drawback to governance I see is it would be more difficult to carry out forks/implement changes, as top producers/witnesses would act in a more decentralized environment.

Edit:
If I read this chart properly, only 3 colluded accounts decide on top 21 producers.