No rumors yet, but I expect it will happen sometime mid-2025.
Curious what parts of the EX you want for MX? The bigger battery? Or perhaps the new modes? Everything about the EX is focused on offroad riding; not MX. So besides stripping the lights and changing rear wheel and tire, one would have to go in and completely overhaul the suspension springs and valving for MX. And, the EX frame is made to be more compliant for enduro rather than the MX-specific flex. I submit you are not really getting anything substantial by selling an MX to buy an EX to then update the EX to MX specs. If you don't own a Varg, seems like same answer. Buy a current Varg MX for $11,000 and ride it rather than buying EX for $14,000 then throwing another $2k - $3 at the suspension and wheels. Or, wait for the Varg MX to get the same updates. Can't be too far out. I suspect they will update the MX sometime next summer as soon as current inventory is sold out and the part bins are empty of current Varg MX parts. Who knows. They may even announce it over the winter and those that ordered MX now for next year delivery may get the new MX at the price they lock in now.