It literally couldn’t grow that much. It can only go from 1/4 of the web to 4/4 of the web. :)
I Always give a 110%, maybe my math is wrong!
What makes you think that it would grow its adoption rate at all? If I were to take a guess, I'd say most Wordpress installations are done by people who don't care about server load, and don't fret out over a 2s load time instead of 200ms.
In fact, that was the way Moveable Type worked and was a dominant publishing tool before WordPress took off.