Holika's statement means next to nothing about the length of the season or the expansion release timeline. Read the rest of his tweets on the topic, especially "Trying to break the trend of long seasons to end the expac. People are reading waaaaay too much into it," and "I definitely did NOT say the new PvP season would last around 20-25 weeks. I'd say that's the max length I'd want it."
If the current season lasts around 20 weeks, and the following season lasts
less than 20 weeks, a June release is still perfectly possible. Nothing is certain or confirmed based on this statement.