Not sure how serious nor how hard Trump will push for this. Opponents will say that a national sales tax will be hard to implement. As much as that may be, getting rid of the unconstitutional, loophole ridden income tax is important on two fronts. Making the tax system fairer and less burdensome on the economy but even more so because it removes the incentive to borrow money(debt).

Currently, every business and wealthy individuals, utilize massive amounts of debt to acquire assets, especially real estate. They then get to write off the interest from their taxes. If you get rid of income tax you remove the incentive to borrow.

When the benefit of a writeoff gets removed, a project or asset has to generate large enough returns to warrant making the investment. Not only does this result in a fairer tax system but it is much better in having capital flow into more productive, beneficial investments.