That's not going to happen as long a Gaia Plate and Canadia exist. Megarock Dragon simply isn't as good as Gaia Plate, and much, much weaker to Canadia. (And Forbidden Chalice, amongst other things.)
The amount of resources it takes to get it to a worthwhile ATK without That Grass Looks Greener (which can also facilitate things like Berserkion and Delta, who are ultimately better anyway) is simply not worth it. Gaia Plate takes less setup, and is virtually always a better beatstick. This is very similar to Tyranno Infinity. Seems decent in theory, but isn't really worth it.
why use that grass looks greener card when this field spell does all the work for you without the cost of potential losing spell/traps.. speaking of tyranno infinity i got a dino deck to KOG 2 months back with infinity as my ace card for the win so for myself i see quite abit of potential for mega rock to become great.. you just need to know what your doing