If this is going to be just another LF2 mod, even if you resprite every single sprite in the game to awesome level, it won't be successful..
Only way to make this happen is buying whole game from U1 and creating intersting game mechanics such as playing at several levels, more complex maps with barriers and with different paths, more complex storyline/stage more, HQ sprites and more awesome innovations...., but still keeping simplicity of DCing and sprites because that is what brought huge success to LF2 in first place. So it will be cool looking fighting game (maybe introducing it with option to play as rpg game in stage mod, there are not limits), but still easily changeable by any newbie because that will lead to further audience.
EDIT V: I wouldn't say successor for HF because LF2 is still more popular game than HF and it will always be due to immutability of HF codes.
Only way to make this happen is buying whole game from U1 and creating intersting game mechanics such as playing at several levels, more complex maps with barriers and with different paths, more complex storyline/stage more, HQ sprites and more awesome innovations...., but still keeping simplicity of DCing and sprites because that is what brought huge success to LF2 in first place. So it will be cool looking fighting game (maybe introducing it with option to play as rpg game in stage mod, there are not limits), but still easily changeable by any newbie because that will lead to further audience.
EDIT V: I wouldn't say successor for HF because LF2 is still more popular game than HF and it will always be due to immutability of HF codes.