So for the time being, I think an Assa is out of the question, and rightly so.
The rogue in D4 partly fills out the gameplay of the assassin. There may well be another such class, but it is likely to be half a decade away.
That a likely Valkyrie is coming next I find extremely interesting and the idea of it being a mix of holy warrior with spear and shield actually appeals to me much much more than a Paladin, which I remember as the least interesting class from D2. I’m just not a paladin player, but I do like significantly more of a spear fighter with holy and or lightning abilities that fit well with a melee style of combat. It just shouldn’t seem too godly and overdone with effects, but rather authentically down to earth and as one of us, so to speak.
If you turn the Valkyrie into such an over-the-top thing and inflate it into a kitschy fairy tale, then I’m more likely to be repulsed by it. But if it comes more in the Viking style and fits in well as a normal being, then it will pull me in.
What could come after that in terms of class, probably Blizz themselves do not even really know 100%.
It should just fit into the game and not tear the game apart. In the end, the game must work as a game to remain interesting. It is not advisable to degenerate it in any way through strange classes, always more colorful, faster or as an end-game game to grave to carry, because the actual game world becomes irrelevant and numbers and items bury the rest.
If I’m going to speculate, I’m guessing after the Valkyrie, if it comes, there will be a rather sinister class that springs from the ranks of demonic forces and has been corrupted.
And it will tend to be more of a mixed class of magic and something, or a pure magic class.
But I don’t think it will be an assassin.
Personally, I would like a Rune Master as a mage or a Rune Blacksmith as a mixed class of Rune Magic combined with a thick two-handed hammer or one-handed hammer weapon + shield. The latter is rather unlikely, but a Rune Mage would be more conceivable. At the same time it is solid, not a completely unknown exotic seen from class history and this class has maximum potential, is very implementable and has very many possibilities to bring in good class story on all levels.
It would be very different from the rest in almost all aspects and would have a strong slowed down gameplay to offer with rune symbols with wonderful effect possibilities, as well as a chance at dwarven race integration, which could greatly expand the game itself.
So a class that can bring in a maximum of content an innovation, which would do the game good and could also expand it wonderfully through zones, such as a dwarven city/realm for example.
But this is all pure wishful thinking.
What really awaits us…I don’t know…