There is a lot of speculation here.
First of all ICANN is not going to allow extensions under 3 letters, or extensions similar to others. So you are not going to see .COM typos, or .USA when there is a .US
Second, there is no way this happens anytime soon other than possibly TM names because.
1.) This will be a nightmare for Google, and without Google this is a non starter.
2.) If you think people who own domains like Sex.com, XXX.com, Poker.com, etc. won't lock this up in court for years you are dreaming.
There are just as many big time rich owners of those premium domains now that will fight to protect their brand.