Yes, building a new code base is what Maxon works on for several years now (when I remember right, it began with R13) and this is progressive task. So, most likely it will take another 3-5(or even more, maybe less) releases to completely move to this basis.
Besides that, new features will also have to be built based on that, existing ones have to be rebuilt. C4D has decent and extremely good MT implementation yet, that's why Cinebench is so fast on multithreaded machines and used by chip vendors to show of their capabilites.
And to conclude this, keep in mind that there are cases where multithreading makes things slower.
By the way, writing down things like "This and that will be in next release" isn't helpful for anyone. That only leads to confusion and disappointment.