Well, Axl's transforming power is decent, and his flexibility with a large array of weapons is nice, but I'd like to see some form of Magic, or as the futuristic world of Sega's PSU puts it, FORCE. Also, the hover from X5 did bring some help for X. In addition, Sigma will be much weaker than his form leads on, revealing Lumine is back for vengence.
Plus, X did get a redesign during the Elf Wars, so that and Zero's redesign are both nessessary.
Also, considering the "New Character" thing, I'd think of having that as an unlock thing to get people to beat the game.
I'm thinking the new character should be a Create-A-Character, meaning you can go through the story again, but with a character of your design added to the roster.
Plus, though it was somewhat clunky, the X7 3D Mode wasn't all that bad. Give some improvement and it could be a lot better.
In addition, Dynamo was killed in X6, I hope ya'll know.