While I definitely agree there's a similarity, I feel Activision actually does a much better job maintaining their brands as a whole.
To be fair, it's a lot more difficult to keep the attentions of kids over an extended period of time than to keep the attention of teenagers and adults. When you're aiming at kids, there's always the next cool thing on the horizon (while the kids that liked your "old" stuff are growing out of it), so if you don't think that you've got a really great "evergreen" brand on your hand, it's a better bet to milk the popularity for as long as you are popular.
Of course, it's entirely possible that Level-5 has got their hands on a brand that has the potential to stay, but I doubt they expected this kind of success. They wanted a successor to Inazuma and got something that dwarfs it by comparison. It doesn't look like launching YK2 so soon is a mistake either. To the contrary, it feels like it's firing up the hype even more.
It'll be interesting to see how Level-5 handles the franchise from now on, though, considering that YK2's release date was probably already set (internally) before the anime made YK a phenomenon in Japan. Will they milk it further or are they going to handle it more carefully than their past franchises?
Either way, Level-5 will come up with the next franchise eventually. Some of their new IPs might not set the world on fire, but they've proven that it's always just a matter of time before they find something new.