We are at 8.42, of course there are no plans for A9. And to be specific, jcl has stated often in the past that there are no thoughts about A7 / A8. Especially when the engine is at version X.5 or X.4.
I would be disappointed if A9 comes out in a few months, because i would feel a bit ripped of, assuming that a new version comes out every three years. Because it would mean that I have to invest money.

In the past new engine versions have not contributed "killer features". The engine evolves rather independend from its (integer) version numbers, at least that's my experience with gamestudio.

Edit: ok, I have to admit that in june A8 is indeed 3 years old. So it would be time for a new version. Ah well, time flies by....