According to new research from PricewaterhouseCoopers (PwC) - a firm that labels itself a "powerhouse" of a commercial enterprise - this move will come ten years earlier than previously predicted.
The study revealed the effects of the global financial crisis means the upsurge of nations such as China, India and Brazil will see their assets catching up to those of the likes of the UK and the US sooner rather than later.
In 2009, UK banking assets were ranked as the fourth greatest in the world, behind the US, China and Japan.
John Hawksworth, chief economist of PwC, said: "In the long term, therefore, the success of UK banks will depend a lot on their ability to compete in the fast-growing emerging market."
The G7 group of countries was formed in 1975 and initially consisted of the US, the UK, France, Germany, Japan and Italy, with Canada invited a year later.
By Tony Aynsley