No doubt a tube through the "center" is not only a LONG way off, it is not that useful either...not much in the Norther Hemisphere..where most of the travelers would be based goes to any other place that would be a serious destination.
But the Secant Tube might be much closer in the future....Think hubs like airports...NYC to Chicago to Dallas and SF...all 42 minute legs and not too deep and without the major effects of the earth rotating like any tube through the center...except pole to pole...a very low traffic route anyway.