CLOSE the .SU cctld, please!
Here is some important reasons:
The Soviet Union doesn't exist more than 15 years!
For users, it's sometimes quite difficult to remember cctld for each domain name in Russian Fed. and try to change .SU to .RU and vice versa if something goes wrong (i.e phishing, pop-ups, a lot of adult or illegal content etc.).
.US and .SU are quite similar and it's easy to misarrange characters or to make a criminal activity using social engineering techniques.
Basically .SU is popular only by cybersquatters, there are only a few companies or communities which can't get .RU domain name (because of cybersquatters).
Sometimes it's emolumentary for fishing & spam only! (as you know there are many spammers and dishonest people from Russian Fed. and formerly Soviet Union).
Nowadays there are no more than 800,000 domains totally in Russian Fed. and it absolutely doesn't requred the SECOND country-code.