The new w change really isn't that great, I mean he already has a ton of AOE as it is, what does this really give him that his Q and E can't already? Okay % health damage but the area for it is very small which makes it unreliable to gauge when it will even apply or not. They're trying to give him more power but this change seems underwhelming by itself.
Other changes that would really spruce up gragas would be removing the 1 second channel on W and increasing the damage reduction timer. To be perfectly honest I don't like how repetitious the ability is to begin with but I doubt that it will be changed significantly in any way.