What you think, if cursor is like combofire.I mean, to have change after reaching certain combo.Like this in the sliders, but it will work with the combo sistem.I think it can be done. 
One example.
cursor1.png from 1 to 100 combo
cursor2.png from 101 to 250 combo
cursor3.png from 251 to 500 combo
cursor4.png from 501 to 750 combo
cursor5.png from 751 to 1000 combo and so on.
The colors are just a preview up there (like a rising temperature in the stars).You can do it with some hieroglyph to be changed to another.The ideas are infinite.
And if can be done for the cursortrail.png as well because will look ugly if only one of them is changing
That will allow players to custom it and I know that will happen if we can do it.
I will do it myself for my skin in osu.
P.S. You can do upgrade in the sorting songs in the game, but it's not for this request.
I'm sorry for my poor english.
One example.
cursor1.png from 1 to 100 combo
cursor2.png from 101 to 250 combo
cursor3.png from 251 to 500 combo
cursor4.png from 501 to 750 combo
cursor5.png from 751 to 1000 combo and so on.
The colors are just a preview up there (like a rising temperature in the stars).You can do it with some hieroglyph to be changed to another.The ideas are infinite.
And if can be done for the cursortrail.png as well because will look ugly if only one of them is changing
That will allow players to custom it and I know that will happen if we can do it.
I will do it myself for my skin in osu.
P.S. You can do upgrade in the sorting songs in the game, but it's not for this request.
I'm sorry for my poor english.