Mechanical Violator Hakaider takes place in the original manga's universe.Unfortunately, SHADOW won and reduced the world to various city-states with surviving generals, such as Gurjev, acting as dictators. Multiple Hakaider units were created to act as special law enforcement. When Ryo went rogue, Gurjev salvaged the destroyed Kikaider and modified him into Michael.
There will be a sequel to Kikaider: REBOOTIt'll need to follow on from the mid-credits scene at the end of REBOOT, but other than that either it will be a modern adaptation of Kikaider 01 (either the toku or the manga/anime's take on it), or it will involve the Inazuman from Movie War Ultimatum, adapting the manga chapter where Kikaider and Inazuman fought that was adapted for the ending of the anime and the Code 02 manga. And it will be AWESOME.