They’re theoretically going to be frozen, not seized.
More likely that it pushes south florida real estate prices even higher even faster. Just the perception and expectation should do that. Less units that could even be on the market.
I expect them to be firesaled by the oligarches themselves. Get them liquidated before they're frozen, and get that desperately needed western currency that doesn't need to flow through embargoed Russian banks; a desperation life raft.