The largest shareholder in Wizz, I believe, is the American investment company Indigo Partners who also have a large investment in Ryanair and recently bought Frontier Airlines in the US - so you can make that of what you will.
As regards a rebrand IMHO I cannot see the need for this - Wizz is very well known in Eastern Europe and becoming increasingly well known now in other parts of the Continent and the UK with an outstanding colour scheme on its aircraft.