I expect 10-15 years of dongle hell as we wait for the old cars to reach end-of-life. Then once everything's settled down, battery chemistry improvements will prompt a migration to the MCS connector for faster DC charging.
Though Tesla is claiming "up to 1MW" for the connector. Perhaps 100 kWh in 6 minutes is good enough for the foreseeable future of passenger road vehicles, even if MCS would be ~4X faster.