Despite the challenges the Republican tax overhaul faces, Goldman Sachs still puts the chances of a plan becoming law by early next year at about 65 percent — but its analysts see some substantial changes coming before that happens. “The proposed tax cut is more front-loaded than we have expected; official estimates suggest a tax cut of 0.75% of GDP in 2018. However, we expect the final version to have a smaller near-term effect as competing priorities lead tax-writers to phase in some cuts—particularly corporate rate cuts—over time,” Goldman said in a note to clients Sunday.