According to FEI entries (which are sometimes incomplete), only Belarus and Russia will compete + an individual from Latvia. Kind of meh, I expected to see Poland and Estonia as well, though it's possible they felt like Russia was unbeatable anyway. Actually, only Belarus could possibly challenge the Russians, and even that is rather unlikely.
Russia though very much deserves to finally qualify a dressage team. They never had a team after the Soviet times during which they were rather successful. Hell, they even defeated West Germany for the team gold at the Munich Olympics.