Do the banks have an 'end game' for branches?

They'll go online-only. Some 10 years after online-only banks not only existed but had proven themselves viable. If you haven't noticed, high-streets are dying and turning into a few same franchises in every town, and the big superstores are moving out of town. Same thing. Bricks and mortar is far too expensive and getting worse. Think how many massive store chains have gone out of business or applied for insolvency or been taken over in the last couple of decades: Woolworths, C&A, BHS, Maplins, Carpetright, The Body Shop, Currys/Dixons, Lloyds Pharmacy, Wilko, Peacocks, OddBins, Debenhams, Thomas Cook, Bonmarché, Mothercare, Clintons, Jessops, Supercuts, Brighthouse, Victoria's Secret, Monsoon Accessorize, Oak Furnitureland, Poundstretcher, Go Outdoors, Benson Beds, Harveys, .... Pretty much every UK high street store chain at some point or another. The high-street is dead. Physical banks aren't necessary (I've been with an online-only bank for nearly 10 years now). They've been cutting back staff, facilities, locations for over a decade already. There is only one inevitable outcome - banks going entirely online, and cash goes the way of the dodo, and high streets (especially in city centres) die off and become residential properties while out-of-town retail parks are where you go for shopping.