That's an interesting question. The idea been that if there is a DMC5 or DmC2 that both would retain nothing from the other is kinda not ganna happen. Things from DmC will go into the next DMC game, be it big or small 'M'. It's like asking what things from DMC will go into DmC 3 years ago, plenty, no question about it.
To answer your question in a more concise way I'll make my own list, too.
#1: The dynamic camera.
DMC1 had a much more lively camera than it's sequels so to see a more creative and active camera in DmC was a plus.
#2: Distance covering options.
The issue with DMC2 and 4 are often how open the spaces are and how hard it is to bring you and you're opponent closer to you. DmC had the grapples, which are nice, but more options would also be encouraged. Bayonetta had attacks that could reach her opponents from great distances, grapples that took her to her enemy or vice versa, and a teleport, not to mention she could jump high and cover more distance with her dodge to close the gaps plus a panther run. Any way, one method to close the distance between you and your target is great but 5 is the tits.
Now for the things they need to add.
#1: Lock-on.
No excuses or BS explanations, just put the thing back where it was. Do I use the lock on every single time I fight? No, I don't use it that often but I use it none the less and it's there for a good reason. Taking away options is no progressive.
#2: Enough with this 'accessing all weapons on the fly' garbage.
It's great that you can call up eight different weapons on the fly but why, oh, sweet dear lord, can we not get more than that. DMC3 had 10 weapons to choose from, Bayonetta had like 20, having you're own customized set is a positive, I don't mind going to the pause menu and changing it so go ahead and give me more variety. I don't understand why they think that all the weapons should be accessible at all times. If they can come up with more intuitive ways to add more slots for on the fly switching, great! But if not I don't mind taking the time to arrange my own set that includes a bunch of very different things, just give me to option to do it, though.
That is it for now. I think everything else has already been mentioned or discussed so I'm set.