NG4? You underestimate TN's love for rehashing NG titles. I'll bet we see NG3 again before NG4.
Ahahaha xD
Sarcasm aside, I doubt we're gonna see another version of NG3.
While another version of DoA5 for X1 and PS4 is likely imho, with the addition of the Arcade version and even more.
I guess I wouldn't mind it.
As for NG I have mixed feelings. My favourite remains the first title for several, several, several reasons.
NG1 allowed you to play in several different ways. You could go a more strategic, defensive, slow approach. Or you could go all out on action and be very fast and offensive.
Moveset didn't feel particularly buttonmashing and while there were clearly moves more efficient than others, overall each weapon had a good selection of useful combos, and you noticed that utillity (guard break etc) especially at higher difficulty levels. I loved this freedom of approach, I loved the exploration and backtracking, I loved the fact that it was all a single, huge, connected level. An inventory to manage! Loved it.
NG2 moved away from that, it became a more linear game, while there was a bit of exploration, there hardly was backtracking. Levels were basically a linear path from starting point A to ending point B. More emphasis on action.
Weapons had too many moves, many were button-mashy and combos were often too long.
The % of useful moves among the list decreased as the movesets themselves increased.
The game didn't offer as much freedom in the "approach" you could take to play the game.
It kinda forced you to stay on the offensive, always, no matter what.
Less importance of the inventory.
Despite these changes that I didn't like, it still was an incredibly awesome game.
NG3, especially the first version, was a huge failure under maybe every point of view. Even less exploration, uninspired levels, dumb cut-scenes, ugly plot, superbuttonmashy combos, no levelup for weapons (did I say weapons? I should have said weapon, singular) altough technically the list of moves went up as you received different swords throughout the game.
The new handling of Ninpos and UT was ugly.
Razor's Edge tried to address many of these aspects, but while the overall final result was apreciable, you could still feel that it was good things patched up over a "broken" core. You can't fix that "broken" core because it was badly designed to begin with.
Given what players "want" (action action action! flashes! Superfast!) I doubt they'll ever return to the roots of NG1, but if they try to do something similar to the NG2 "compromise" I'll be happy enough.
In the end I have to say that while it surprises me a lot to say it, I don't think the connections between NG and DoA worked out particularly good. I'm talking about the bonus characters, especially in NG3 Razor's Edge..
I think it would have been better to keep the connection through story and cut-scenes without allowing you to actually USE those bonus characters. It especially felt bad to be able to play the whole game with those characters in NG3 compared to the special levels of NG1 and NG2.