Don't get me wrong, I'd want DR3 to conclude whatever build-up it's supposed to be leading to with the Future Foundation stuff with DR2's ending, but I'm not sure I necessarily agree with the above. I suppose AA has the advantage of having a small group of recurring characters between titles (minus AA4), but doesn't DR also follow the procedural nature that the AA series has, with the different murders?
Not exactly... in AA all cases can exist entirely separate to each other. That's not always the case*, but basically an AA case only requires a crime - not even necessarily murder - and an attorney. Everything else is pretty open.
But in DR, all the murders are linked to one bigger conspiracy. It's basically inevitable, the cast only rotates between games not cases. The Killing Game will have to be linked to despair/Junko/Monokuma in some way, I'm sure there's a way around it like a flashback - the ORIGINAL secret killing game 20 years ago! feat Junko's parents - but essentially you're running the same routine over and over with variations on who dies. AA has a lot more freedom with the elements it uses*. As mentioned by posts after mine, there's a limit to how many Ultimates there are, who can be orchestrating killing games, etc.
On a personal note, I just want the series to end because many parts of DR1 and DR2 are frustratingly vague and a clear conclusion would mean that they don't have to keep cards close to the chest anymore.
*one of the reasons I'm not a huge fan of Takeshi Yamazaki's AA titles is he tends to force links between all the cases and tries to tie everything into a big narrative when it isn't necessary. Heck I wish AA had less killing in general, I really liked the cases in which kidnapping and theft were big plot points.