The Department of the Treasury is steadily making progress on writing guidance for the Tax Cuts and Jobs Act and have announced a tentative release schedule: June/July for the passthrough deduction, late summer/early fall for the new limitations on interest expense, and December for the big international provisions (e.g. GILTI and BEAT).
In the meantime, the Committee on Ways and Means is contemplating a second round of tax cuts, or Tax Reform 2.0 as they like to call it. They are aiming to make permanent the new individual provisions as well as full expensing for businesses.