IMO either a) more or b) less globalization make sense, not the current level.
Real people and real (SME + micro) companies need a real economy, local, national, regional (eg EU, ASEAN, Mercosur, etc) and global (WTO area) and real policies to create real growth + real jobs, not virtual ones.
Who "elected" the G20 as a new world economic "government"? IMO neither the G8 or G20 have the political legitimacy to formulate world economic policy and make decisions - global democratic deficit.
Should the WTO instead of the G20 assume the role of the G8 in "world governance"?
There are many legit ways to achieve a democratic governance system that will include most of the world (Earth), but the ones being put forward are not them.
Maybe the EU or the US are models for a World Union or a United States of the World. Other, more complicated models exist too, IMO. But any legit model can to entail the participation of the people (democracy) concerned.
8 or 20 or 50 countries cannot formulate policies or make decisions that affect the rest of the countries and their people (members of UN or at least the WTO).