- take away (arrest, freeze, whatever) the elite's real estate in the west
- same thing with other assets, banc accounts etc
- ban them from living in the west or going to the west on vacation, for medical treatment.
- ban their families from living in the west, their kids from studying there.
this is not my idea, you will find similar suggestions a hundred times in different forms on the Russian-speaking internet.
maybe there is no legal base right now to do it as described, but the alternative is broad sanctions that hit the small people harder then regime collaborators.
edit: formatting