I can say two things: 1) Good Karate (or any martial arts) is good---and bad is bad; and 2) Human nature is what it is.

For the first, you can tell and see when something is good by experiencing it. For the second, just about any art that did not have the founder mandating a particular heir (and even if he did) there will be infighting and contentiousness to take the throne that was vacated by the king.

If you have very good and talented managers, they will find themselves out of the shadow of the founder and now have the ability to strike out on their own without feeling that sense of obligation and connection to the source of their education.

For Kyokushin, the family chose Midori Kenji and others chose Matsui.

As long as you have good instruction, then that's good enough.

Human nature, as strange as it is, will have some choosing themselves as the next in line. And in every case of a founder of a particular martial art passing away, I have always noted a break up of the organization when the founder's charisma and abilities are no longer there to cement that organization together.