This didn't work out so well for the aborigines. Regardless, Britain couldn't have controlled the U.S. colonies in any meaningful way for very long after 1780.
They were having major trouble keeping the Americans from attempting to steal land and exterminate the inhabitants even before then. British colonial policies usually didn't exactly coincide with both what Americans wanted and what Americans actually were doing. This inability to control far-off territories on the ground was a staple of Early Modern Atlantic Empires.
The British had been using Native Americans for hundred plus years before that anyway to offset both other colonial powers in North America like the French and the Spanish and to assist them in creating an economic regime, providing perverse incentives to indigenous groups to enslave each other and drawing them into economic dependence via trade. The demographic disasters of disease and enslavement directly served to push Native American groups into cycles of dependence, obliterating long-standing cultural lifeways and producing new indigenous socio-political orders that could not withstand the floodgates of American land greed the Revolution unleashed.
