They have cemented themselves in global music history. Anyone living in this period of time will remember them, even non fans, seeing how their enlistment news was going viral among local twt with some even getting 300k likes.
It may be possible for BTS achievements like album sales(due to inflation) or a much more popular group to come close to their streams and charting. But these achievements will always be mentioned next to BTS and they will remain the standard for a long long time just like the Beatles and other big legacy acts still hold onto records till this day.
That’s what BTS impact will be in kpop.