Nice ideas, i wrote earlier about i similar system to change the effects in different ways 
were having a debate over on
https://us.forums.blizzard.com/en/d3/t/runewords-are-very-possible-within-the-new-system/10313/2
if the unique runeword items should have main stats and stuff or the unique runeword only should be an empowerment of the effect of the combined rune 