i dont think it'll be fully implemented, i believe there is more of a focus on variable valve actuation systems with pneumatic actuators, than a complex mechanical system, vtec was a good advancement in pollution control, but even more valve systems will be a necessity as pollution controls become even stricter, but these advanced variable valve systems are becoming less experimental and have already began prototype testing in the newer fuel efficient hybrid cars honda engineers are making nowadays. try doing a search for pneumatically controlled variable valve systems, they go into depth on how they can control both the valve openning and closing different amounts and also for different time periods all along the rpm band.