To make a Hybrid work, it NEEDS an engine. Thats why it's called a Hybrid. Synergy between a regular engine, and battery power. So engines will continue to be built to make any Hybrid work unless the vehicle is 100% electric...when then we have to build more power-plants to keep up with demand that those electric vehicles would require.
Plus, hybrid has not yet taken off, and many are still questioning it's future. Other than cost which many are not willing to pay, the jury is still out as to it's reliability, and the depreciation it'll have on the vehicles that will need new battery packs 5-8 years from now. Not everyone can plunk down $5,000 for a new battery pack.
Like any new technology, it'll be many more years and billions more in investments to take us to another level.